Today's Message Index:
----------------------
1. 12:46 AM - Re: Yak-52 Brake Cables (Rob Kent - WLAC Russian Engineering)
2. 01:08 AM - Re: Yak-52 Brake Cables (Rob Kent - WLAC Russian Engineering)
3. 06:20 AM - Re: Copper Tubing Replacement -- Easiest thing around... (david stroud)
4. 02:15 PM - White Paper on Russian Generator System (Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E)
5. 04:38 PM - Re: White Paper on Russian Generator System (Terry Lewis)
6. 04:43 PM - Re: Re: Yak-52 Brake Cables (Craig Payne)
7. 04:44 PM - Re: White Paper on Russian Generator System (Terry Lewis)
8. 04:44 PM - Re: White Paper on Russian Generator System (Terry Lewis)
9. 08:19 PM - Re: White Paper on Russian Generator System (Rob Rowe)
10. 09:27 PM - Re: Re: White Paper on Russian Generator System (KingCJ6@aol.com)
11. 10:11 PM - Re: White Paper on Russian Generator System (Jan Mevis)
12. 10:49 PM - Re: Re: White Paper on Russian Generator System (ByronMFox@aol.com)
Message 1
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| Subject: | Re: Yak-52 Brake Cables |
Hi John,
Unfortunately I cannot help you with demand for cables. I have a dozen
original cables due in from Aerostar sometime in the next couple of weeks
and they have cost me less than $110 each. My sales price is likely to be
around 78 ($150ea). I usually have a good stock of these but sold the last
two or three in a short period of time.
Regards
Rob Kent
Stores Manager
WLAC - Russian Engineering
www.wlacrussianeng.co.uk
Tel: +44 1628 829 165
Fax: +44 1628 825 975
Mob: +44 7842 964 358
----- Original Message -----
From: "John A. Nielsen" <john@nielsenford.com>
Sent: Tuesday, February 13, 2007 8:16 PM
Subject: Yak-List: Yak-52 Brake Cables
>
> I am about to produce a direct replacement brake cable for a Yak 52.
> (the one that terminates at the forward control stick). The original
> got pinched as it went through the floor. I can get a
> break on price for qty of 12 or more.
>
> Price is expected be $110 plus shipping. All components are AN hardware
> and cable is SS.
>
> Can you all help me with demand for an initial order? Reply to this
> message or to my e-mail directly.
>
> Thank you.
>
> John Nielsen
> www.NielsenFord.com
> www.HighPerformanceAircraftProducts.com
> Bloomer WI
> Cell: 715-829-6512
>
>
>
Message 2
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| Subject: | Re: Yak-52 Brake Cables |
Are these not usually readily available in the USA from the likes of Carl
Hayes and George Coy? I don't understand the need to have them made when the
originals are easy enough and cheap enough to obtain.
Regards
Rob Kent
Stores Manager
WLAC - Russian Engineering
www.wlacrussianeng.co.uk
Tel: +44 1628 829 165
Fax: +44 1628 825 975
Mob: +44 7842 964 358
----- Original Message -----
From: "John A. Nielsen" <john@nielsenford.com>
Sent: Tuesday, February 13, 2007 8:16 PM
Subject: Yak-List: Yak-52 Brake Cables
>
> I am about to produce a direct replacement brake cable for a Yak 52.
> (the one that terminates at the forward control stick). The original
> got pinched as it went through the floor. I can get a
> break on price for qty of 12 or more.
>
> Price is expected be $110 plus shipping. All components are AN hardware
> and cable is SS.
>
> Can you all help me with demand for an initial order? Reply to this
> message or to my e-mail directly.
>
> Thank you.
>
> John Nielsen
> www.NielsenFord.com
> www.HighPerformanceAircraftProducts.com
> Bloomer WI
> Cell: 715-829-6512
>
>
>
Message 3
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| Subject: | Re: Copper Tubing Replacement -- Easiest thing around... |
Giday Walt. That was a fine little dissertation on the tube fitting the
other day. I've
got to plan ahead for my fuel and brake tubing and was wondering if you
know of a
website available outlining the howto's, do's and don'ts for a good
installation.
By the way, Walt...your name, along with a few others was written in the
back of
one of my Fairchild 24 manuals . C-FDAE was the registration of the 24 I
got out
of Prince George but it spend some time down near Vancouver too. Small
world.
My engine got sent down to Colorado to be installed in the original
Smilin' Jack
F24 and the airframe went to Cincinnati.
David Stroud Ottawa, Canada
C-FDWS Christavia
Fairchild 51 under construction
and on the gear...
Message 4
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| Subject: | White Paper on Russian Generator System |
YAK-50 DC Power Generation and Troubleshooting by Mark Bitterlich N50YK
Warning: This is a technical explanation of the power generation,
regulation, and connection to aircraft main's of the typical
Yak-50/52/55 or Sukhoi-26/29/31. It is offered for those that have at
least a general understanding of electronics. In all cases where
voltage from power supplies or from batteries were connected for
testing, circuit breakers were installed for safety. If anyone tries to
follow these notes and duplicate my efforts, beware... if you make
mistakes, or fail to include current limiting devices such as light
bulbs and circuit breakers/fuses, you could easily cause serious damage
to aircraft wiring. Ok.. so I had to cover my six. That said, let's
move on.
I just spent the last few days learning my YAK-50's electrical power
generation system. Thanks for all of those that sent schematics of what
you had on hand. Every person contributed towards solving this puzzle!
THANKS TO EVERYONE! The specifics in some regards focus on the YAK-50,
although all of the Yak's and Sukhoi's use close to the same design with
some slight wiring differences here and there. The important thing is
that in most cases the parts are all identical. Of course this does not
include "Westernized" designs, such as the 52W, 52TW, etc. Most of
these have already had B&C (or other) products installed.
Power generation starts with the generator. This is a 3 KW monster that
is capable of 100 amps output if properly cooled. This same generator
can operate at 30 amps intermittent duty with no cooling air.
There are 3 wires on the generator, + positive, - negative, and what the
Russians refer to as "Shunting Input". This input is actually what
controls the generator output and is normally called "Field Excitation".
This generator has a very well designed voltage regulation system using
a carbon pile voltage regulator that controls field voltage within a +2
/ -2 volt range. Voltage output is also stabilized with a bucking
transformer known in Russian as "The Stabilizing Transformer". If you
want to see examples of systems like this, go back to WW-II designs and
you will see the exact same thing. In other words, this is 60 year old
technology and you need to go back and read about some of the theory
involved, because like a bucking transformer, you rarely see these
components in today's designs, but they were very common before the
discovery of high current voltage regulation transistors.
Basically, most of the system is self starting and self contained
regulating in a closed loop circuit. As soon as the generator starts
spinning, it will put out voltage although at idle it will be much lower
than 28 volts and it will not be connected into the aircraft mains. As
RPM comes up and voltage rises, it will eventually stabilize at the
rated voltage set by the carbon pile regulator. So, if you have any
kind of problem, the first thing you will want to do is to gain access
to the main generator terminals (you have to remove a cover on the
generator) and hook a meter to the PLUS and MINUS connectors with LONG
meter leads so that you can then safely check the voltage when you start
the engine. If your generator is putting out voltage at idle, give it a
quick boost to about 60% or so, and you should see your meter come up to
around 28 voltage (plus or minus a few tenths) and then start
regulating. By "starting to regulate", I mean that the voltage will stop
increasing as you continue to raise engine RPM If you have NO output
voltage, shut the engine off, and then when you are eyeballing the
inside of the generator, slowly move the prop. Does the generator spin?
If so, then that is a good thing. If NOT, then you have sheared a shaft,
replace the generator. If it does rotate, start it back up and run a
test for Field Excitation Voltage. If you have excitation voltage, then
again it is probably a bad generator. If you have no excitation, there
are a few other things that could be wrong, such as the carbon pile
regulator itself, or your over voltage breaker has tripped.
If at any time the generator puts out too much voltage, in the realm of
31.5 volts or so (+/- 0.5 volt) then a circuit breaker will pop on the
over/under voltage detection and protection unit. This is a silver box
with two cannon plugs on it, that is in the nose inspection hole left
side top in the 50, and somewhere else in the 52. I think it is in the
forward cockpit underneath the instrument panel on the 52 but don't
quote me. This unit has a rubber covered breaker button that you can
reach in and reset if you have had an over-voltage condition. It is
another thing to check anytime you have a problem, but typically an
over-voltage trip is not common.
Moving on, the closed loop design has generator output going first to
the stabilization transformer primary winding, then through that
directly to a component called "The Combined Device" also known as the
DMR-200D. This component (the DMR-200D) is located in the gray box
mounted on the firewall, top right side (looking forward) in the 50, and
by the Pilots right foot in the 52. Power goes through a MAIN CONTACTOR
RELAY inside of the Combined Device ONLY IF CERTAIN CONDITIONS ARE MET.
Here is where things get tricky.
Going back the Stabilizing Transformer for a minute, (just to complete
the mental image) main output voltage of the generator goes through the
primary winding as I already mentioned. This is just a few turns of
wire, and offers VERY little resistance. Part of the secondary windings
of this transformer system has outputs going to the voltage regulator
and the over voltage box. The Voltage Regulator (official name "R-27")
has outputs that feed back to control the generator excitation field,
but it also has another output that goes over to the over voltage box.
If the voltage is normal, the over voltage box feeds this same voltage
(28 volts) back to pin B on the Combined Device. (Note, it looks like a
"B" to me, that is the SHAPE of the marking, but it is actually the
Russian letter "V".) This input voltage to pin B (V in Russian) turns
on internal relay TKE-210B INSIDE of the Combined Unit. The
nomenclature of this relay means nothing since you can't see or touch it
without taking the whole thing apart. Just realize that when you put 28
volts to the connection marked "B" and a ground on the connection marked
"-" (for minus), an internal relay will close and it will ENABLE the
rest of the Combined Device. When this first relay closes, it then
enables yet another system inside of the Combined Device known as the
Polarization Relay. The "PR" is a special dual winding relay that will
close only if current flows through the relay coil itself in the proper
direction. If you try to flow current through this relay backwards, it
simply won't work, and that is by design. It is SUPPOSED to do that.
After the Polarization Relay (or PR) is enabled, it has a circuit that
connects it to both the output main terminal and the input main
terminal. If the PR likes what it sees and closes, it then in turn
provides power for yet ANOTHER Relay Coil inside of the Combined Unit,
this one is known as the MAIN POWER CONTACTOR RELAY. This is the big
boss relay in the whole thing, and when it closes, generator power then
comes OUT of the Combined Unit and is fed to the aircraft MAIN BUS BAR.
In other words, the MAIN POWER CONTACTOR actually connects the large
input terminal to the large output terminal on the Combined Unit.
What is really tricky to understand about this whole design is the
Polarization Relay. Consider this: When you turn on the Aircraft
Master, Battery Voltage is fed to the MAIN BUS and as such it also is
fed right down to the large OUTPUT terminal of the Combined Unit. At
this point, the OUTPUT of the Combined Unit is not connected to
ANYTHING, because the MAIN CONTACTOR RELAY is still OPEN. Let's
consider our battery voltage to be a normal. As such, there is about 24
volts on the Combined Units OUTPUT terminal post coming from the battery
with the Aircraft Master switch turned on.
Now let's start the engine. The generator starts to spin. Everything
works properly and as your engine speed comes up, so does generator
voltage. This voltage is now fed to the Combined Unit's INPUT power
terminal. Assuming 28 volts is fed to terminal "B" ("V" in Russian)
thus ENABLING the Combined Unit, you will end up with battery voltage on
one side of the Polarization Relay Coil and Generator Voltage on the
OTHER side of the Polarization Relay Coil. Once there is a difference
in voltage between battery voltage and generator voltage of about 2
volts or so, and the generator voltage is HIGHER than the battery
voltage, the Polarization Relay will CLOSE and will then in turn close
the MAIN POWER CONTACTOR. Once the MAIN POWER CONTACTOR is closed, 28
volts will be fed out terminal "C" which will then in turn close yet
another relay (external to the Combined Device) and turn OFF the
Generator Light in the cockpit. It also then of course is feeding
generator power directly to the aircraft main power bus.
Not done yet! There is yet ANOTHER relay coil in the Combined Device
that is only enabled if the main enabling relay is powered up through
terminal "B" as mentioned earlier. If terminal B has 28 volts, then
terminal "6" becomes active (In Russian the "6" is actually the Russian
letter "B"... confused yet? Easy to do. Just remember that as I write
this, I refer to how they look to me and how they will look to YOU!) If
you put a GROUND on this terminal "6" it will close yet another relay
coil inside of the Combined Device and will REMOVE the generator feed
voltage from the Polarization Relay thus making it INOPERATIVE!
Remember, if you disable the PR relay, then of course you have also
disabled the MAIN CONTACTOR Relay, and thus, no voltage from the
generator will ever make it to the main aircraft bus. The ground on
terminal "6" is usually controlled by the Generator Switch in the
cockpit. And here is a warning... not all Russian designs work like
this. From the Sukhoi to the Yak there are major wiring differences in
how they wire this device, but the general concepts are the same.
Operationally testing a system like this can be difficult at best. I
tried a method that worked for me, but is offered with a Caveat Emptor
warning... buyer beware, your mileage may vary and if you smoke you
whole aircrafts electrical system, DO NOT blame me.
I disconnected all three leads from the generator. I used a small 10
watt 28 VDC light bulb connected to the field winding wire to ground. I
took the main generator PLUS and MINUS wires off of the generator and
hooked them to a 28 volt variable DC power supply of about 20 amps
capacity. DO NOT LEAVE ANY OF THE AIRCRAFTS WIRES CONNECTED TO THE
GENERATOR. The Field Winding can either float or have a SMALL 28 volt
DC light bulb hooked from it to ground.
You can now bring up voltage with the variable supply and check for
voltages at proper locations without having to run the M-14 engine
itself. Initially set the variable supply to about 20 volts. Look for
this 20 volts from the variable power supply at Combined Device Input
terminal. (Right side bottom.. the BIG one). Turn on the Aircraft
Master and look for BATTERY voltage on the OUTPUT terminal (left side
middle of the Combined Device...the OTHER big one) Look for 20 volts on
terminal "B" and NO GROUND on terminal "6". Increase voltage on the
variable supply to 28.0 volts even. As you come up on the voltage, the
MAIN CONTACTOR should close with a loud WHACK. If not, you have
problems with the Combined Device.
Remove the Combined Device and bench check it. Here is how you go about
doing that.
Some of the internal relays can be checked simply by listening to them
click. No, this does not check the relay CONTACTS themselves, but hey,
that comes later. Using a 28 volt source, either battery or variable
supply, connect negative to the (-) terminal on the Combined Device.
Connect 28 volts to terminal B. You should hear a relay click.
Disconnect from B. Now connect 28 volts to terminal A..(It looks sort
of like an A anyway) It is on the right side above the large INPUT
terminal. You should hear a LOUD relay closing, this is the main
contactor. Remove power from "A". Reapply power to "B"... again you
hear a relay click. Leaving power applied to B, now hook a grounded
wire to pin 6. This will close ANOTHER relay and you should be able to
hear it click. You have now checked every relay coil in the Combined
Device, other than the Polarization Relay, and the internal relay
contacts themselves.
Find a 24 volt battery, or hook two 12 volt batteries in series. Hook
the negative lead of the battery to the negative side of your variable
power supply. Also connect a wire from this to the MINUS (-) terminal
on the Combined Device. So all negatives (grounds/earths) are now
common to each other. Hook the plus lead of the battery to the OUTPUT
side of the Combined Device (Big terminal left side middle).
Variable power supply is now OFF.
Apply a wire from the 28 volt variable supply output (plus voltage) to
the MAIN INPUT terminal (bottom right side). Also connect a jumper from
this terminal to terminal "B". Put some voltmeters here and there to
monitor whatever you feel like, but most certainly variable power supply
output voltage. Increase the variable power supply output. When it
reaches about 2 volts or so MORE than the battery voltage, the MAIN
CONTACTOR will close, and you will now have connected your variable
power supply to your test batteries.... and remember, when you do this,
you have just created a battery charger, and the variable power supply
will now try to start charging the batteries! If your variable power
supply is too small, as soon as it starts to try and charge the
batteries through the now closed MAIN CONTACTOR RELAY, the variable
power supply voltage will DROP. This will trigger the Polarization
Relay to OPEN, then causing the MAIN CONTACTOR to open as well, and
battery charging will cease... at which point the variable power supply
will jump back up in voltage, the polarization relay will close again
and the whole cycle will repeat. This event happens very fast and will
make a lot of noise. So... warning... use a variable power supply that
can handle more than a few amps without voltage drop for this test. A
regulated supply that is variable as well would be ideal.
Ok, so what if the MAIN CONTACTOR does NOT energize when you increase
the voltage? More than likely, you have problems with the Polarization
Relay. This device seems to wear out first, and the word has it that you
can take this Combined Device apart and adjust these contacts to fix
this relay. I have not done that yet, but am getting ready to.
The Combined Device is a rather rare animal and sooner or later is going
to give us all a certain amount of grief. Without a doubt, I suspect if
we continue to fly these aircraft we are going to have to get more of
these devices at a reasonable cost, or build our own, or convert the
whole aircraft power generation system over to American made. The
latter is probably the best idea over the long run.
So there you have it. The methods for testing this system are my own
and not adopted from any other manual or article. Use them at your own
risk. Feel free to copy and distribute this article as you see fit, but
I would sincerely appreciate it if you left my name on it as the author.
Addendum:
Every Russian aircraft owner should take a careful look at the Carbon
Pile Voltage Regulator R-27. Vladimir Yastremski warned me about this
device, and his warning was dead on accurate. This device is mounted on
a very very loose shock mount and rocks and rolls all over the place in
flight. It has wires that screw onto terminals and as the thing moves,
it can cause a short circuit to certain terminals. Sure enough, on my
YAK-50, one of the terminals was blackened by a short circuit. As I
moved the whole thing around, I could see how it caused the short.
Second, look at all the wiring that goes anywhere near bulkheads and/or
"bulb angle". It is common to see chaffing here, and sure enough... I
had another wire burnt almost in two by short circuits in THIS area.
So, bottom line, 50 owners... save yourself a lot of grief and get you
head up into that nose equipment compartment and inspect all wiring
CAREFULLY!!!
Best of Luck to all who decide to fix problems with this system on their
own... it's not easy, but this article should help you get started at
least.
Mark Bitterlich
N50YK
Message 5
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| Subject: | Re: White Paper on Russian Generator System |
Mark,
This is a great look at the YAK 50 Russian electrical system that would
apply to most of the Russian electrical systems of that era.
Nice job!
This type of information will help maintain these aircraft in good working
order.
Information that people like You and Dennis and Walt and Doug many others
share with the group will make this a safer operation.
Thanks,
Terry Lewis
----- Original Message -----
From: "Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E"
<mark.bitterlich@navy.mil>
Sent: Wednesday, February 14, 2007 5:14 PM
Subject: Yak-List: White Paper on Russian Generator System
> MALS-14 64E" <mark.bitterlich@navy.mil>
>
> YAK-50 DC Power Generation and Troubleshooting by Mark Bitterlich N50YK
>
> Warning: This is a technical explanation of the power generation,
> regulation, and connection to aircraft main's of the typical
> Yak-50/52/55 or Sukhoi-26/29/31. It is offered for those that have at
> least a general understanding of electronics. In all cases where
> voltage from power supplies or from batteries were connected for
> testing, circuit breakers were installed for safety. If anyone tries to
> follow these notes and duplicate my efforts, beware... if you make
> mistakes, or fail to include current limiting devices such as light
> bulbs and circuit breakers/fuses, you could easily cause serious damage
> to aircraft wiring. Ok.. so I had to cover my six. That said, let's
> move on.
>
> I just spent the last few days learning my YAK-50's electrical power
> generation system. Thanks for all of those that sent schematics of what
> you had on hand. Every person contributed towards solving this puzzle!
> THANKS TO EVERYONE! The specifics in some regards focus on the YAK-50,
> although all of the Yak's and Sukhoi's use close to the same design with
> some slight wiring differences here and there. The important thing is
> that in most cases the parts are all identical. Of course this does not
> include "Westernized" designs, such as the 52W, 52TW, etc. Most of
> these have already had B&C (or other) products installed.
>
> Power generation starts with the generator. This is a 3 KW monster that
> is capable of 100 amps output if properly cooled. This same generator
> can operate at 30 amps intermittent duty with no cooling air.
>
> There are 3 wires on the generator, + positive, - negative, and what the
> Russians refer to as "Shunting Input". This input is actually what
> controls the generator output and is normally called "Field Excitation".
> This generator has a very well designed voltage regulation system using
> a carbon pile voltage regulator that controls field voltage within a +2
> / -2 volt range. Voltage output is also stabilized with a bucking
> transformer known in Russian as "The Stabilizing Transformer". If you
> want to see examples of systems like this, go back to WW-II designs and
> you will see the exact same thing. In other words, this is 60 year old
> technology and you need to go back and read about some of the theory
> involved, because like a bucking transformer, you rarely see these
> components in today's designs, but they were very common before the
> discovery of high current voltage regulation transistors.
>
> Basically, most of the system is self starting and self contained
> regulating in a closed loop circuit. As soon as the generator starts
> spinning, it will put out voltage although at idle it will be much lower
> than 28 volts and it will not be connected into the aircraft mains. As
> RPM comes up and voltage rises, it will eventually stabilize at the
> rated voltage set by the carbon pile regulator. So, if you have any
> kind of problem, the first thing you will want to do is to gain access
> to the main generator terminals (you have to remove a cover on the
> generator) and hook a meter to the PLUS and MINUS connectors with LONG
> meter leads so that you can then safely check the voltage when you start
> the engine. If your generator is putting out voltage at idle, give it a
> quick boost to about 60% or so, and you should see your meter come up to
> around 28 voltage (plus or minus a few tenths) and then start
> regulating. By "starting to regulate", I mean that the voltage will stop
> increasing as you continue to raise engine RPM If you have NO output
> voltage, shut the engine off, and then when you are eyeballing the
> inside of the generator, slowly move the prop. Does the generator spin?
> If so, then that is a good thing. If NOT, then you have sheared a shaft,
> replace the generator. If it does rotate, start it back up and run a
> test for Field Excitation Voltage. If you have excitation voltage, then
> again it is probably a bad generator. If you have no excitation, there
> are a few other things that could be wrong, such as the carbon pile
> regulator itself, or your over voltage breaker has tripped.
>
> If at any time the generator puts out too much voltage, in the realm of
> 31.5 volts or so (+/- 0.5 volt) then a circuit breaker will pop on the
> over/under voltage detection and protection unit. This is a silver box
> with two cannon plugs on it, that is in the nose inspection hole left
> side top in the 50, and somewhere else in the 52. I think it is in the
> forward cockpit underneath the instrument panel on the 52 but don't
> quote me. This unit has a rubber covered breaker button that you can
> reach in and reset if you have had an over-voltage condition. It is
> another thing to check anytime you have a problem, but typically an
> over-voltage trip is not common.
>
> Moving on, the closed loop design has generator output going first to
> the stabilization transformer primary winding, then through that
> directly to a component called "The Combined Device" also known as the
> DMR-200D. This component (the DMR-200D) is located in the gray box
> mounted on the firewall, top right side (looking forward) in the 50, and
> by the Pilots right foot in the 52. Power goes through a MAIN CONTACTOR
> RELAY inside of the Combined Device ONLY IF CERTAIN CONDITIONS ARE MET.
> Here is where things get tricky.
>
> Going back the Stabilizing Transformer for a minute, (just to complete
> the mental image) main output voltage of the generator goes through the
> primary winding as I already mentioned. This is just a few turns of
> wire, and offers VERY little resistance. Part of the secondary windings
> of this transformer system has outputs going to the voltage regulator
> and the over voltage box. The Voltage Regulator (official name "R-27")
> has outputs that feed back to control the generator excitation field,
> but it also has another output that goes over to the over voltage box.
> If the voltage is normal, the over voltage box feeds this same voltage
> (28 volts) back to pin B on the Combined Device. (Note, it looks like a
> "B" to me, that is the SHAPE of the marking, but it is actually the
> Russian letter "V".) This input voltage to pin B (V in Russian) turns
> on internal relay TKE-210B INSIDE of the Combined Unit. The
> nomenclature of this relay means nothing since you can't see or touch it
> without taking the whole thing apart. Just realize that when you put 28
> volts to the connection marked "B" and a ground on the connection marked
> "-" (for minus), an internal relay will close and it will ENABLE the
> rest of the Combined Device. When this first relay closes, it then
> enables yet another system inside of the Combined Device known as the
> Polarization Relay. The "PR" is a special dual winding relay that will
> close only if current flows through the relay coil itself in the proper
> direction. If you try to flow current through this relay backwards, it
> simply won't work, and that is by design. It is SUPPOSED to do that.
>
>
> After the Polarization Relay (or PR) is enabled, it has a circuit that
> connects it to both the output main terminal and the input main
> terminal. If the PR likes what it sees and closes, it then in turn
> provides power for yet ANOTHER Relay Coil inside of the Combined Unit,
> this one is known as the MAIN POWER CONTACTOR RELAY. This is the big
> boss relay in the whole thing, and when it closes, generator power then
> comes OUT of the Combined Unit and is fed to the aircraft MAIN BUS BAR.
> In other words, the MAIN POWER CONTACTOR actually connects the large
> input terminal to the large output terminal on the Combined Unit.
>
> What is really tricky to understand about this whole design is the
> Polarization Relay. Consider this: When you turn on the Aircraft
> Master, Battery Voltage is fed to the MAIN BUS and as such it also is
> fed right down to the large OUTPUT terminal of the Combined Unit. At
> this point, the OUTPUT of the Combined Unit is not connected to
> ANYTHING, because the MAIN CONTACTOR RELAY is still OPEN. Let's
> consider our battery voltage to be a normal. As such, there is about 24
> volts on the Combined Units OUTPUT terminal post coming from the battery
> with the Aircraft Master switch turned on.
>
> Now let's start the engine. The generator starts to spin. Everything
> works properly and as your engine speed comes up, so does generator
> voltage. This voltage is now fed to the Combined Unit's INPUT power
> terminal. Assuming 28 volts is fed to terminal "B" ("V" in Russian)
> thus ENABLING the Combined Unit, you will end up with battery voltage on
> one side of the Polarization Relay Coil and Generator Voltage on the
> OTHER side of the Polarization Relay Coil. Once there is a difference
> in voltage between battery voltage and generator voltage of about 2
> volts or so, and the generator voltage is HIGHER than the battery
> voltage, the Polarization Relay will CLOSE and will then in turn close
> the MAIN POWER CONTACTOR. Once the MAIN POWER CONTACTOR is closed, 28
> volts will be fed out terminal "C" which will then in turn close yet
> another relay (external to the Combined Device) and turn OFF the
> Generator Light in the cockpit. It also then of course is feeding
> generator power directly to the aircraft main power bus.
>
> Not done yet! There is yet ANOTHER relay coil in the Combined Device
> that is only enabled if the main enabling relay is powered up through
> terminal "B" as mentioned earlier. If terminal B has 28 volts, then
> terminal "6" becomes active (In Russian the "6" is actually the Russian
> letter "B"... confused yet? Easy to do. Just remember that as I write
> this, I refer to how they look to me and how they will look to YOU!) If
> you put a GROUND on this terminal "6" it will close yet another relay
> coil inside of the Combined Device and will REMOVE the generator feed
> voltage from the Polarization Relay thus making it INOPERATIVE!
> Remember, if you disable the PR relay, then of course you have also
> disabled the MAIN CONTACTOR Relay, and thus, no voltage from the
> generator will ever make it to the main aircraft bus. The ground on
> terminal "6" is usually controlled by the Generator Switch in the
> cockpit. And here is a warning... not all Russian designs work like
> this. From the Sukhoi to the Yak there are major wiring differences in
> how they wire this device, but the general concepts are the same.
>
> Operationally testing a system like this can be difficult at best. I
> tried a method that worked for me, but is offered with a Caveat Emptor
> warning... buyer beware, your mileage may vary and if you smoke you
> whole aircrafts electrical system, DO NOT blame me.
>
> I disconnected all three leads from the generator. I used a small 10
> watt 28 VDC light bulb connected to the field winding wire to ground. I
> took the main generator PLUS and MINUS wires off of the generator and
> hooked them to a 28 volt variable DC power supply of about 20 amps
> capacity. DO NOT LEAVE ANY OF THE AIRCRAFTS WIRES CONNECTED TO THE
> GENERATOR. The Field Winding can either float or have a SMALL 28 volt
> DC light bulb hooked from it to ground.
>
> You can now bring up voltage with the variable supply and check for
> voltages at proper locations without having to run the M-14 engine
> itself. Initially set the variable supply to about 20 volts. Look for
> this 20 volts from the variable power supply at Combined Device Input
> terminal. (Right side bottom.. the BIG one). Turn on the Aircraft
> Master and look for BATTERY voltage on the OUTPUT terminal (left side
> middle of the Combined Device...the OTHER big one) Look for 20 volts on
> terminal "B" and NO GROUND on terminal "6". Increase voltage on the
> variable supply to 28.0 volts even. As you come up on the voltage, the
> MAIN CONTACTOR should close with a loud WHACK. If not, you have
> problems with the Combined Device.
>
> Remove the Combined Device and bench check it. Here is how you go about
> doing that.
>
> Some of the internal relays can be checked simply by listening to them
> click. No, this does not check the relay CONTACTS themselves, but hey,
> that comes later. Using a 28 volt source, either battery or variable
> supply, connect negative to the (-) terminal on the Combined Device.
> Connect 28 volts to terminal B. You should hear a relay click.
> Disconnect from B. Now connect 28 volts to terminal A..(It looks sort
> of like an A anyway) It is on the right side above the large INPUT
> terminal. You should hear a LOUD relay closing, this is the main
> contactor. Remove power from "A". Reapply power to "B"... again you
> hear a relay click. Leaving power applied to B, now hook a grounded
> wire to pin 6. This will close ANOTHER relay and you should be able to
> hear it click. You have now checked every relay coil in the Combined
> Device, other than the Polarization Relay, and the internal relay
> contacts themselves.
>
> Find a 24 volt battery, or hook two 12 volt batteries in series. Hook
> the negative lead of the battery to the negative side of your variable
> power supply. Also connect a wire from this to the MINUS (-) terminal
> on the Combined Device. So all negatives (grounds/earths) are now
> common to each other. Hook the plus lead of the battery to the OUTPUT
> side of the Combined Device (Big terminal left side middle).
>
> Variable power supply is now OFF.
>
> Apply a wire from the 28 volt variable supply output (plus voltage) to
> the MAIN INPUT terminal (bottom right side). Also connect a jumper from
> this terminal to terminal "B". Put some voltmeters here and there to
> monitor whatever you feel like, but most certainly variable power supply
> output voltage. Increase the variable power supply output. When it
> reaches about 2 volts or so MORE than the battery voltage, the MAIN
> CONTACTOR will close, and you will now have connected your variable
> power supply to your test batteries.... and remember, when you do this,
> you have just created a battery charger, and the variable power supply
> will now try to start charging the batteries! If your variable power
> supply is too small, as soon as it starts to try and charge the
> batteries through the now closed MAIN CONTACTOR RELAY, the variable
> power supply voltage will DROP. This will trigger the Polarization
> Relay to OPEN, then causing the MAIN CONTACTOR to open as well, and
> battery charging will cease... at which point the variable power supply
> will jump back up in voltage, the polarization relay will close again
> and the whole cycle will repeat. This event happens very fast and will
> make a lot of noise. So... warning... use a variable power supply that
> can handle more than a few amps without voltage drop for this test. A
> regulated supply that is variable as well would be ideal.
>
> Ok, so what if the MAIN CONTACTOR does NOT energize when you increase
> the voltage? More than likely, you have problems with the Polarization
> Relay. This device seems to wear out first, and the word has it that you
> can take this Combined Device apart and adjust these contacts to fix
> this relay. I have not done that yet, but am getting ready to.
>
> The Combined Device is a rather rare animal and sooner or later is going
> to give us all a certain amount of grief. Without a doubt, I suspect if
> we continue to fly these aircraft we are going to have to get more of
> these devices at a reasonable cost, or build our own, or convert the
> whole aircraft power generation system over to American made. The
> latter is probably the best idea over the long run.
>
> So there you have it. The methods for testing this system are my own
> and not adopted from any other manual or article. Use them at your own
> risk. Feel free to copy and distribute this article as you see fit, but
> I would sincerely appreciate it if you left my name on it as the author.
>
>
> Addendum:
>
> Every Russian aircraft owner should take a careful look at the Carbon
> Pile Voltage Regulator R-27. Vladimir Yastremski warned me about this
> device, and his warning was dead on accurate. This device is mounted on
> a very very loose shock mount and rocks and rolls all over the place in
> flight. It has wires that screw onto terminals and as the thing moves,
> it can cause a short circuit to certain terminals. Sure enough, on my
> YAK-50, one of the terminals was blackened by a short circuit. As I
> moved the whole thing around, I could see how it caused the short.
> Second, look at all the wiring that goes anywhere near bulkheads and/or
> "bulb angle". It is common to see chaffing here, and sure enough... I
> had another wire burnt almost in two by short circuits in THIS area.
> So, bottom line, 50 owners... save yourself a lot of grief and get you
> head up into that nose equipment compartment and inspect all wiring
> CAREFULLY!!!
>
> Best of Luck to all who decide to fix problems with this system on their
> own... it's not easy, but this article should help you get started at
> least.
>
> Mark Bitterlich
> N50YK
>
>
>
Message 6
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| Subject: | Re: Re: Yak-52 Brake Cables |
>Are these not usually readily available in the USA from the likes of Carl
>Hayes and George Coy? I don't understand the need to have them made when the
>originals are easy enough and cheap enough to obtain.
>
>Regards
>
>Rob Kent
>
>
Much like the CJ cables, what I have seen are steel cables with soldered balls
on each end. The lead-tin ball ends tend to work harden and pull through and cables
corode from moisture in the housings.
Not as reliable as modern stainless steel cables with swaged ball & shank ends.
These I have after having the brake cable pull through the ball end on a crowded
ramp.
I can also get these made in batches for the CJ.
Craig Payne
cpayne@joimail.com
Message 7
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| Subject: | Re: White Paper on Russian Generator System |
Mark,
This is a great look at the YAK 50 Russian electrical system that would
apply to most of the Russian electrical systems of that era.
Nice job!
Sharing this type of information ,with this group ,will help maintain these
aircraft in good working order.
Information that people like You and Dennis and Walt and Doug and many
others share makes these aircraft safer to operate and easier to maintain .
We appreciate it .
Thanks,
Terry Lewis
----- Original Message -----
From: "Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E"
<mark.bitterlich@navy.mil>
Sent: Wednesday, February 14, 2007 5:14 PM
Subject: Yak-List: White Paper on Russian Generator System
> MALS-14 64E" <mark.bitterlich@navy.mil>
>
> YAK-50 DC Power Generation and Troubleshooting by Mark Bitterlich N50YK
>
> Warning: This is a technical explanation of the power generation,
> regulation, and connection to aircraft main's of the typical
> Yak-50/52/55 or Sukhoi-26/29/31. It is offered for those that have at
> least a general understanding of electronics. In all cases where
> voltage from power supplies or from batteries were connected for
> testing, circuit breakers were installed for safety. If anyone tries to
> follow these notes and duplicate my efforts, beware... if you make
> mistakes, or fail to include current limiting devices such as light
> bulbs and circuit breakers/fuses, you could easily cause serious damage
> to aircraft wiring. Ok.. so I had to cover my six. That said, let's
> move on.
>
> I just spent the last few days learning my YAK-50's electrical power
> generation system. Thanks for all of those that sent schematics of what
> you had on hand. Every person contributed towards solving this puzzle!
> THANKS TO EVERYONE! The specifics in some regards focus on the YAK-50,
> although all of the Yak's and Sukhoi's use close to the same design with
> some slight wiring differences here and there. The important thing is
> that in most cases the parts are all identical. Of course this does not
> include "Westernized" designs, such as the 52W, 52TW, etc. Most of
> these have already had B&C (or other) products installed.
>
> Power generation starts with the generator. This is a 3 KW monster that
> is capable of 100 amps output if properly cooled. This same generator
> can operate at 30 amps intermittent duty with no cooling air.
>
> There are 3 wires on the generator, + positive, - negative, and what the
> Russians refer to as "Shunting Input". This input is actually what
> controls the generator output and is normally called "Field Excitation".
> This generator has a very well designed voltage regulation system using
> a carbon pile voltage regulator that controls field voltage within a +2
> / -2 volt range. Voltage output is also stabilized with a bucking
> transformer known in Russian as "The Stabilizing Transformer". If you
> want to see examples of systems like this, go back to WW-II designs and
> you will see the exact same thing. In other words, this is 60 year old
> technology and you need to go back and read about some of the theory
> involved, because like a bucking transformer, you rarely see these
> components in today's designs, but they were very common before the
> discovery of high current voltage regulation transistors.
>
> Basically, most of the system is self starting and self contained
> regulating in a closed loop circuit. As soon as the generator starts
> spinning, it will put out voltage although at idle it will be much lower
> than 28 volts and it will not be connected into the aircraft mains. As
> RPM comes up and voltage rises, it will eventually stabilize at the
> rated voltage set by the carbon pile regulator. So, if you have any
> kind of problem, the first thing you will want to do is to gain access
> to the main generator terminals (you have to remove a cover on the
> generator) and hook a meter to the PLUS and MINUS connectors with LONG
> meter leads so that you can then safely check the voltage when you start
> the engine. If your generator is putting out voltage at idle, give it a
> quick boost to about 60% or so, and you should see your meter come up to
> around 28 voltage (plus or minus a few tenths) and then start
> regulating. By "starting to regulate", I mean that the voltage will stop
> increasing as you continue to raise engine RPM If you have NO output
> voltage, shut the engine off, and then when you are eyeballing the
> inside of the generator, slowly move the prop. Does the generator spin?
> If so, then that is a good thing. If NOT, then you have sheared a shaft,
> replace the generator. If it does rotate, start it back up and run a
> test for Field Excitation Voltage. If you have excitation voltage, then
> again it is probably a bad generator. If you have no excitation, there
> are a few other things that could be wrong, such as the carbon pile
> regulator itself, or your over voltage breaker has tripped.
>
> If at any time the generator puts out too much voltage, in the realm of
> 31.5 volts or so (+/- 0.5 volt) then a circuit breaker will pop on the
> over/under voltage detection and protection unit. This is a silver box
> with two cannon plugs on it, that is in the nose inspection hole left
> side top in the 50, and somewhere else in the 52. I think it is in the
> forward cockpit underneath the instrument panel on the 52 but don't
> quote me. This unit has a rubber covered breaker button that you can
> reach in and reset if you have had an over-voltage condition. It is
> another thing to check anytime you have a problem, but typically an
> over-voltage trip is not common.
>
> Moving on, the closed loop design has generator output going first to
> the stabilization transformer primary winding, then through that
> directly to a component called "The Combined Device" also known as the
> DMR-200D. This component (the DMR-200D) is located in the gray box
> mounted on the firewall, top right side (looking forward) in the 50, and
> by the Pilots right foot in the 52. Power goes through a MAIN CONTACTOR
> RELAY inside of the Combined Device ONLY IF CERTAIN CONDITIONS ARE MET.
> Here is where things get tricky.
>
> Going back the Stabilizing Transformer for a minute, (just to complete
> the mental image) main output voltage of the generator goes through the
> primary winding as I already mentioned. This is just a few turns of
> wire, and offers VERY little resistance. Part of the secondary windings
> of this transformer system has outputs going to the voltage regulator
> and the over voltage box. The Voltage Regulator (official name "R-27")
> has outputs that feed back to control the generator excitation field,
> but it also has another output that goes over to the over voltage box.
> If the voltage is normal, the over voltage box feeds this same voltage
> (28 volts) back to pin B on the Combined Device. (Note, it looks like a
> "B" to me, that is the SHAPE of the marking, but it is actually the
> Russian letter "V".) This input voltage to pin B (V in Russian) turns
> on internal relay TKE-210B INSIDE of the Combined Unit. The
> nomenclature of this relay means nothing since you can't see or touch it
> without taking the whole thing apart. Just realize that when you put 28
> volts to the connection marked "B" and a ground on the connection marked
> "-" (for minus), an internal relay will close and it will ENABLE the
> rest of the Combined Device. When this first relay closes, it then
> enables yet another system inside of the Combined Device known as the
> Polarization Relay. The "PR" is a special dual winding relay that will
> close only if current flows through the relay coil itself in the proper
> direction. If you try to flow current through this relay backwards, it
> simply won't work, and that is by design. It is SUPPOSED to do that.
>
>
> After the Polarization Relay (or PR) is enabled, it has a circuit that
> connects it to both the output main terminal and the input main
> terminal. If the PR likes what it sees and closes, it then in turn
> provides power for yet ANOTHER Relay Coil inside of the Combined Unit,
> this one is known as the MAIN POWER CONTACTOR RELAY. This is the big
> boss relay in the whole thing, and when it closes, generator power then
> comes OUT of the Combined Unit and is fed to the aircraft MAIN BUS BAR.
> In other words, the MAIN POWER CONTACTOR actually connects the large
> input terminal to the large output terminal on the Combined Unit.
>
> What is really tricky to understand about this whole design is the
> Polarization Relay. Consider this: When you turn on the Aircraft
> Master, Battery Voltage is fed to the MAIN BUS and as such it also is
> fed right down to the large OUTPUT terminal of the Combined Unit. At
> this point, the OUTPUT of the Combined Unit is not connected to
> ANYTHING, because the MAIN CONTACTOR RELAY is still OPEN. Let's
> consider our battery voltage to be a normal. As such, there is about 24
> volts on the Combined Units OUTPUT terminal post coming from the battery
> with the Aircraft Master switch turned on.
>
> Now let's start the engine. The generator starts to spin. Everything
> works properly and as your engine speed comes up, so does generator
> voltage. This voltage is now fed to the Combined Unit's INPUT power
> terminal. Assuming 28 volts is fed to terminal "B" ("V" in Russian)
> thus ENABLING the Combined Unit, you will end up with battery voltage on
> one side of the Polarization Relay Coil and Generator Voltage on the
> OTHER side of the Polarization Relay Coil. Once there is a difference
> in voltage between battery voltage and generator voltage of about 2
> volts or so, and the generator voltage is HIGHER than the battery
> voltage, the Polarization Relay will CLOSE and will then in turn close
> the MAIN POWER CONTACTOR. Once the MAIN POWER CONTACTOR is closed, 28
> volts will be fed out terminal "C" which will then in turn close yet
> another relay (external to the Combined Device) and turn OFF the
> Generator Light in the cockpit. It also then of course is feeding
> generator power directly to the aircraft main power bus.
>
> Not done yet! There is yet ANOTHER relay coil in the Combined Device
> that is only enabled if the main enabling relay is powered up through
> terminal "B" as mentioned earlier. If terminal B has 28 volts, then
> terminal "6" becomes active (In Russian the "6" is actually the Russian
> letter "B"... confused yet? Easy to do. Just remember that as I write
> this, I refer to how they look to me and how they will look to YOU!) If
> you put a GROUND on this terminal "6" it will close yet another relay
> coil inside of the Combined Device and will REMOVE the generator feed
> voltage from the Polarization Relay thus making it INOPERATIVE!
> Remember, if you disable the PR relay, then of course you have also
> disabled the MAIN CONTACTOR Relay, and thus, no voltage from the
> generator will ever make it to the main aircraft bus. The ground on
> terminal "6" is usually controlled by the Generator Switch in the
> cockpit. And here is a warning... not all Russian designs work like
> this. From the Sukhoi to the Yak there are major wiring differences in
> how they wire this device, but the general concepts are the same.
>
> Operationally testing a system like this can be difficult at best. I
> tried a method that worked for me, but is offered with a Caveat Emptor
> warning... buyer beware, your mileage may vary and if you smoke you
> whole aircrafts electrical system, DO NOT blame me.
>
> I disconnected all three leads from the generator. I used a small 10
> watt 28 VDC light bulb connected to the field winding wire to ground. I
> took the main generator PLUS and MINUS wires off of the generator and
> hooked them to a 28 volt variable DC power supply of about 20 amps
> capacity. DO NOT LEAVE ANY OF THE AIRCRAFTS WIRES CONNECTED TO THE
> GENERATOR. The Field Winding can either float or have a SMALL 28 volt
> DC light bulb hooked from it to ground.
>
> You can now bring up voltage with the variable supply and check for
> voltages at proper locations without having to run the M-14 engine
> itself. Initially set the variable supply to about 20 volts. Look for
> this 20 volts from the variable power supply at Combined Device Input
> terminal. (Right side bottom.. the BIG one). Turn on the Aircraft
> Master and look for BATTERY voltage on the OUTPUT terminal (left side
> middle of the Combined Device...the OTHER big one) Look for 20 volts on
> terminal "B" and NO GROUND on terminal "6". Increase voltage on the
> variable supply to 28.0 volts even. As you come up on the voltage, the
> MAIN CONTACTOR should close with a loud WHACK. If not, you have
> problems with the Combined Device.
>
> Remove the Combined Device and bench check it. Here is how you go about
> doing that.
>
> Some of the internal relays can be checked simply by listening to them
> click. No, this does not check the relay CONTACTS themselves, but hey,
> that comes later. Using a 28 volt source, either battery or variable
> supply, connect negative to the (-) terminal on the Combined Device.
> Connect 28 volts to terminal B. You should hear a relay click.
> Disconnect from B. Now connect 28 volts to terminal A..(It looks sort
> of like an A anyway) It is on the right side above the large INPUT
> terminal. You should hear a LOUD relay closing, this is the main
> contactor. Remove power from "A". Reapply power to "B"... again you
> hear a relay click. Leaving power applied to B, now hook a grounded
> wire to pin 6. This will close ANOTHER relay and you should be able to
> hear it click. You have now checked every relay coil in the Combined
> Device, other than the Polarization Relay, and the internal relay
> contacts themselves.
>
> Find a 24 volt battery, or hook two 12 volt batteries in series. Hook
> the negative lead of the battery to the negative side of your variable
> power supply. Also connect a wire from this to the MINUS (-) terminal
> on the Combined Device. So all negatives (grounds/earths) are now
> common to each other. Hook the plus lead of the battery to the OUTPUT
> side of the Combined Device (Big terminal left side middle).
>
> Variable power supply is now OFF.
>
> Apply a wire from the 28 volt variable supply output (plus voltage) to
> the MAIN INPUT terminal (bottom right side). Also connect a jumper from
> this terminal to terminal "B". Put some voltmeters here and there to
> monitor whatever you feel like, but most certainly variable power supply
> output voltage. Increase the variable power supply output. When it
> reaches about 2 volts or so MORE than the battery voltage, the MAIN
> CONTACTOR will close, and you will now have connected your variable
> power supply to your test batteries.... and remember, when you do this,
> you have just created a battery charger, and the variable power supply
> will now try to start charging the batteries! If your variable power
> supply is too small, as soon as it starts to try and charge the
> batteries through the now closed MAIN CONTACTOR RELAY, the variable
> power supply voltage will DROP. This will trigger the Polarization
> Relay to OPEN, then causing the MAIN CONTACTOR to open as well, and
> battery charging will cease... at which point the variable power supply
> will jump back up in voltage, the polarization relay will close again
> and the whole cycle will repeat. This event happens very fast and will
> make a lot of noise. So... warning... use a variable power supply that
> can handle more than a few amps without voltage drop for this test. A
> regulated supply that is variable as well would be ideal.
>
> Ok, so what if the MAIN CONTACTOR does NOT energize when you increase
> the voltage? More than likely, you have problems with the Polarization
> Relay. This device seems to wear out first, and the word has it that you
> can take this Combined Device apart and adjust these contacts to fix
> this relay. I have not done that yet, but am getting ready to.
>
> The Combined Device is a rather rare animal and sooner or later is going
> to give us all a certain amount of grief. Without a doubt, I suspect if
> we continue to fly these aircraft we are going to have to get more of
> these devices at a reasonable cost, or build our own, or convert the
> whole aircraft power generation system over to American made. The
> latter is probably the best idea over the long run.
>
> So there you have it. The methods for testing this system are my own
> and not adopted from any other manual or article. Use them at your own
> risk. Feel free to copy and distribute this article as you see fit, but
> I would sincerely appreciate it if you left my name on it as the author.
>
>
> Addendum:
>
> Every Russian aircraft owner should take a careful look at the Carbon
> Pile Voltage Regulator R-27. Vladimir Yastremski warned me about this
> device, and his warning was dead on accurate. This device is mounted on
> a very very loose shock mount and rocks and rolls all over the place in
> flight. It has wires that screw onto terminals and as the thing moves,
> it can cause a short circuit to certain terminals. Sure enough, on my
> YAK-50, one of the terminals was blackened by a short circuit. As I
> moved the whole thing around, I could see how it caused the short.
> Second, look at all the wiring that goes anywhere near bulkheads and/or
> "bulb angle". It is common to see chaffing here, and sure enough... I
> had another wire burnt almost in two by short circuits in THIS area.
> So, bottom line, 50 owners... save yourself a lot of grief and get you
> head up into that nose equipment compartment and inspect all wiring
> CAREFULLY!!!
>
> Best of Luck to all who decide to fix problems with this system on their
> own... it's not easy, but this article should help you get started at
> least.
>
> Mark Bitterlich
> N50YK
>
>
Message 8
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| Subject: | Re: White Paper on Russian Generator System |
Mark,
This is a great look at the YAK 50 Russian electrical system that would
apply to most of the Russian electrical systems of that era.
Nice job!
Sharing this type of information ,with this group ,will help maintain these
aircraft in good working order.
Information that people like You and Dennis and Walt and Doug and many
others share makes these aircraft safer to operate and easier to maintain .
We appreciate it .
Thanks,
Terry Lewis
----- Original Message -----
From: "Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E"
<mark.bitterlich@navy.mil>
Sent: Wednesday, February 14, 2007 5:14 PM
Subject: Yak-List: White Paper on Russian Generator System
> MALS-14 64E" <mark.bitterlich@navy.mil>
>
> YAK-50 DC Power Generation and Troubleshooting by Mark Bitterlich N50YK
>
> Warning: This is a technical explanation of the power generation,
> regulation, and connection to aircraft main's of the typical
> Yak-50/52/55 or Sukhoi-26/29/31. It is offered for those that have at
> least a general understanding of electronics. In all cases where
> voltage from power supplies or from batteries were connected for
> testing, circuit breakers were installed for safety. If anyone tries to
> follow these notes and duplicate my efforts, beware... if you make
> mistakes, or fail to include current limiting devices such as light
> bulbs and circuit breakers/fuses, you could easily cause serious damage
> to aircraft wiring. Ok.. so I had to cover my six. That said, let's
> move on.
>
> I just spent the last few days learning my YAK-50's electrical power
> generation system. Thanks for all of those that sent schematics of what
> you had on hand. Every person contributed towards solving this puzzle!
> THANKS TO EVERYONE! The specifics in some regards focus on the YAK-50,
> although all of the Yak's and Sukhoi's use close to the same design with
> some slight wiring differences here and there. The important thing is
> that in most cases the parts are all identical. Of course this does not
> include "Westernized" designs, such as the 52W, 52TW, etc. Most of
> these have already had B&C (or other) products installed.
>
> Power generation starts with the generator. This is a 3 KW monster that
> is capable of 100 amps output if properly cooled. This same generator
> can operate at 30 amps intermittent duty with no cooling air.
>
> There are 3 wires on the generator, + positive, - negative, and what the
> Russians refer to as "Shunting Input". This input is actually what
> controls the generator output and is normally called "Field Excitation".
> This generator has a very well designed voltage regulation system using
> a carbon pile voltage regulator that controls field voltage within a +2
> / -2 volt range. Voltage output is also stabilized with a bucking
> transformer known in Russian as "The Stabilizing Transformer". If you
> want to see examples of systems like this, go back to WW-II designs and
> you will see the exact same thing. In other words, this is 60 year old
> technology and you need to go back and read about some of the theory
> involved, because like a bucking transformer, you rarely see these
> components in today's designs, but they were very common before the
> discovery of high current voltage regulation transistors.
>
> Basically, most of the system is self starting and self contained
> regulating in a closed loop circuit. As soon as the generator starts
> spinning, it will put out voltage although at idle it will be much lower
> than 28 volts and it will not be connected into the aircraft mains. As
> RPM comes up and voltage rises, it will eventually stabilize at the
> rated voltage set by the carbon pile regulator. So, if you have any
> kind of problem, the first thing you will want to do is to gain access
> to the main generator terminals (you have to remove a cover on the
> generator) and hook a meter to the PLUS and MINUS connectors with LONG
> meter leads so that you can then safely check the voltage when you start
> the engine. If your generator is putting out voltage at idle, give it a
> quick boost to about 60% or so, and you should see your meter come up to
> around 28 voltage (plus or minus a few tenths) and then start
> regulating. By "starting to regulate", I mean that the voltage will stop
> increasing as you continue to raise engine RPM If you have NO output
> voltage, shut the engine off, and then when you are eyeballing the
> inside of the generator, slowly move the prop. Does the generator spin?
> If so, then that is a good thing. If NOT, then you have sheared a shaft,
> replace the generator. If it does rotate, start it back up and run a
> test for Field Excitation Voltage. If you have excitation voltage, then
> again it is probably a bad generator. If you have no excitation, there
> are a few other things that could be wrong, such as the carbon pile
> regulator itself, or your over voltage breaker has tripped.
>
> If at any time the generator puts out too much voltage, in the realm of
> 31.5 volts or so (+/- 0.5 volt) then a circuit breaker will pop on the
> over/under voltage detection and protection unit. This is a silver box
> with two cannon plugs on it, that is in the nose inspection hole left
> side top in the 50, and somewhere else in the 52. I think it is in the
> forward cockpit underneath the instrument panel on the 52 but don't
> quote me. This unit has a rubber covered breaker button that you can
> reach in and reset if you have had an over-voltage condition. It is
> another thing to check anytime you have a problem, but typically an
> over-voltage trip is not common.
>
> Moving on, the closed loop design has generator output going first to
> the stabilization transformer primary winding, then through that
> directly to a component called "The Combined Device" also known as the
> DMR-200D. This component (the DMR-200D) is located in the gray box
> mounted on the firewall, top right side (looking forward) in the 50, and
> by the Pilots right foot in the 52. Power goes through a MAIN CONTACTOR
> RELAY inside of the Combined Device ONLY IF CERTAIN CONDITIONS ARE MET.
> Here is where things get tricky.
>
> Going back the Stabilizing Transformer for a minute, (just to complete
> the mental image) main output voltage of the generator goes through the
> primary winding as I already mentioned. This is just a few turns of
> wire, and offers VERY little resistance. Part of the secondary windings
> of this transformer system has outputs going to the voltage regulator
> and the over voltage box. The Voltage Regulator (official name "R-27")
> has outputs that feed back to control the generator excitation field,
> but it also has another output that goes over to the over voltage box.
> If the voltage is normal, the over voltage box feeds this same voltage
> (28 volts) back to pin B on the Combined Device. (Note, it looks like a
> "B" to me, that is the SHAPE of the marking, but it is actually the
> Russian letter "V".) This input voltage to pin B (V in Russian) turns
> on internal relay TKE-210B INSIDE of the Combined Unit. The
> nomenclature of this relay means nothing since you can't see or touch it
> without taking the whole thing apart. Just realize that when you put 28
> volts to the connection marked "B" and a ground on the connection marked
> "-" (for minus), an internal relay will close and it will ENABLE the
> rest of the Combined Device. When this first relay closes, it then
> enables yet another system inside of the Combined Device known as the
> Polarization Relay. The "PR" is a special dual winding relay that will
> close only if current flows through the relay coil itself in the proper
> direction. If you try to flow current through this relay backwards, it
> simply won't work, and that is by design. It is SUPPOSED to do that.
>
>
> After the Polarization Relay (or PR) is enabled, it has a circuit that
> connects it to both the output main terminal and the input main
> terminal. If the PR likes what it sees and closes, it then in turn
> provides power for yet ANOTHER Relay Coil inside of the Combined Unit,
> this one is known as the MAIN POWER CONTACTOR RELAY. This is the big
> boss relay in the whole thing, and when it closes, generator power then
> comes OUT of the Combined Unit and is fed to the aircraft MAIN BUS BAR.
> In other words, the MAIN POWER CONTACTOR actually connects the large
> input terminal to the large output terminal on the Combined Unit.
>
> What is really tricky to understand about this whole design is the
> Polarization Relay. Consider this: When you turn on the Aircraft
> Master, Battery Voltage is fed to the MAIN BUS and as such it also is
> fed right down to the large OUTPUT terminal of the Combined Unit. At
> this point, the OUTPUT of the Combined Unit is not connected to
> ANYTHING, because the MAIN CONTACTOR RELAY is still OPEN. Let's
> consider our battery voltage to be a normal. As such, there is about 24
> volts on the Combined Units OUTPUT terminal post coming from the battery
> with the Aircraft Master switch turned on.
>
> Now let's start the engine. The generator starts to spin. Everything
> works properly and as your engine speed comes up, so does generator
> voltage. This voltage is now fed to the Combined Unit's INPUT power
> terminal. Assuming 28 volts is fed to terminal "B" ("V" in Russian)
> thus ENABLING the Combined Unit, you will end up with battery voltage on
> one side of the Polarization Relay Coil and Generator Voltage on the
> OTHER side of the Polarization Relay Coil. Once there is a difference
> in voltage between battery voltage and generator voltage of about 2
> volts or so, and the generator voltage is HIGHER than the battery
> voltage, the Polarization Relay will CLOSE and will then in turn close
> the MAIN POWER CONTACTOR. Once the MAIN POWER CONTACTOR is closed, 28
> volts will be fed out terminal "C" which will then in turn close yet
> another relay (external to the Combined Device) and turn OFF the
> Generator Light in the cockpit. It also then of course is feeding
> generator power directly to the aircraft main power bus.
>
> Not done yet! There is yet ANOTHER relay coil in the Combined Device
> that is only enabled if the main enabling relay is powered up through
> terminal "B" as mentioned earlier. If terminal B has 28 volts, then
> terminal "6" becomes active (In Russian the "6" is actually the Russian
> letter "B"... confused yet? Easy to do. Just remember that as I write
> this, I refer to how they look to me and how they will look to YOU!) If
> you put a GROUND on this terminal "6" it will close yet another relay
> coil inside of the Combined Device and will REMOVE the generator feed
> voltage from the Polarization Relay thus making it INOPERATIVE!
> Remember, if you disable the PR relay, then of course you have also
> disabled the MAIN CONTACTOR Relay, and thus, no voltage from the
> generator will ever make it to the main aircraft bus. The ground on
> terminal "6" is usually controlled by the Generator Switch in the
> cockpit. And here is a warning... not all Russian designs work like
> this. From the Sukhoi to the Yak there are major wiring differences in
> how they wire this device, but the general concepts are the same.
>
> Operationally testing a system like this can be difficult at best. I
> tried a method that worked for me, but is offered with a Caveat Emptor
> warning... buyer beware, your mileage may vary and if you smoke you
> whole aircrafts electrical system, DO NOT blame me.
>
> I disconnected all three leads from the generator. I used a small 10
> watt 28 VDC light bulb connected to the field winding wire to ground. I
> took the main generator PLUS and MINUS wires off of the generator and
> hooked them to a 28 volt variable DC power supply of about 20 amps
> capacity. DO NOT LEAVE ANY OF THE AIRCRAFTS WIRES CONNECTED TO THE
> GENERATOR. The Field Winding can either float or have a SMALL 28 volt
> DC light bulb hooked from it to ground.
>
> You can now bring up voltage with the variable supply and check for
> voltages at proper locations without having to run the M-14 engine
> itself. Initially set the variable supply to about 20 volts. Look for
> this 20 volts from the variable power supply at Combined Device Input
> terminal. (Right side bottom.. the BIG one). Turn on the Aircraft
> Master and look for BATTERY voltage on the OUTPUT terminal (left side
> middle of the Combined Device...the OTHER big one) Look for 20 volts on
> terminal "B" and NO GROUND on terminal "6". Increase voltage on the
> variable supply to 28.0 volts even. As you come up on the voltage, the
> MAIN CONTACTOR should close with a loud WHACK. If not, you have
> problems with the Combined Device.
>
> Remove the Combined Device and bench check it. Here is how you go about
> doing that.
>
> Some of the internal relays can be checked simply by listening to them
> click. No, this does not check the relay CONTACTS themselves, but hey,
> that comes later. Using a 28 volt source, either battery or variable
> supply, connect negative to the (-) terminal on the Combined Device.
> Connect 28 volts to terminal B. You should hear a relay click.
> Disconnect from B. Now connect 28 volts to terminal A..(It looks sort
> of like an A anyway) It is on the right side above the large INPUT
> terminal. You should hear a LOUD relay closing, this is the main
> contactor. Remove power from "A". Reapply power to "B"... again you
> hear a relay click. Leaving power applied to B, now hook a grounded
> wire to pin 6. This will close ANOTHER relay and you should be able to
> hear it click. You have now checked every relay coil in the Combined
> Device, other than the Polarization Relay, and the internal relay
> contacts themselves.
>
> Find a 24 volt battery, or hook two 12 volt batteries in series. Hook
> the negative lead of the battery to the negative side of your variable
> power supply. Also connect a wire from this to the MINUS (-) terminal
> on the Combined Device. So all negatives (grounds/earths) are now
> common to each other. Hook the plus lead of the battery to the OUTPUT
> side of the Combined Device (Big terminal left side middle).
>
> Variable power supply is now OFF.
>
> Apply a wire from the 28 volt variable supply output (plus voltage) to
> the MAIN INPUT terminal (bottom right side). Also connect a jumper from
> this terminal to terminal "B". Put some voltmeters here and there to
> monitor whatever you feel like, but most certainly variable power supply
> output voltage. Increase the variable power supply output. When it
> reaches about 2 volts or so MORE than the battery voltage, the MAIN
> CONTACTOR will close, and you will now have connected your variable
> power supply to your test batteries.... and remember, when you do this,
> you have just created a battery charger, and the variable power supply
> will now try to start charging the batteries! If your variable power
> supply is too small, as soon as it starts to try and charge the
> batteries through the now closed MAIN CONTACTOR RELAY, the variable
> power supply voltage will DROP. This will trigger the Polarization
> Relay to OPEN, then causing the MAIN CONTACTOR to open as well, and
> battery charging will cease... at which point the variable power supply
> will jump back up in voltage, the polarization relay will close again
> and the whole cycle will repeat. This event happens very fast and will
> make a lot of noise. So... warning... use a variable power supply that
> can handle more than a few amps without voltage drop for this test. A
> regulated supply that is variable as well would be ideal.
>
> Ok, so what if the MAIN CONTACTOR does NOT energize when you increase
> the voltage? More than likely, you have problems with the Polarization
> Relay. This device seems to wear out first, and the word has it that you
> can take this Combined Device apart and adjust these contacts to fix
> this relay. I have not done that yet, but am getting ready to.
>
> The Combined Device is a rather rare animal and sooner or later is going
> to give us all a certain amount of grief. Without a doubt, I suspect if
> we continue to fly these aircraft we are going to have to get more of
> these devices at a reasonable cost, or build our own, or convert the
> whole aircraft power generation system over to American made. The
> latter is probably the best idea over the long run.
>
> So there you have it. The methods for testing this system are my own
> and not adopted from any other manual or article. Use them at your own
> risk. Feel free to copy and distribute this article as you see fit, but
> I would sincerely appreciate it if you left my name on it as the author.
>
>
> Addendum:
>
> Every Russian aircraft owner should take a careful look at the Carbon
> Pile Voltage Regulator R-27. Vladimir Yastremski warned me about this
> device, and his warning was dead on accurate. This device is mounted on
> a very very loose shock mount and rocks and rolls all over the place in
> flight. It has wires that screw onto terminals and as the thing moves,
> it can cause a short circuit to certain terminals. Sure enough, on my
> YAK-50, one of the terminals was blackened by a short circuit. As I
> moved the whole thing around, I could see how it caused the short.
> Second, look at all the wiring that goes anywhere near bulkheads and/or
> "bulb angle". It is common to see chaffing here, and sure enough... I
> had another wire burnt almost in two by short circuits in THIS area.
> So, bottom line, 50 owners... save yourself a lot of grief and get you
> head up into that nose equipment compartment and inspect all wiring
> CAREFULLY!!!
>
> Best of Luck to all who decide to fix problems with this system on their
> own... it's not easy, but this article should help you get started at
> least.
>
> Mark Bitterlich
> N50YK
>
>
Message 9
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| Subject: | Re: White Paper on Russian Generator System |
Hi Mark,
Great diagnostic posting!
>From the schematics ... a few points around the (western) DMD-200D "Complex Apparatus"
for discussion from your description.
1 - the Polarised Relay (II) is of a differential design, comprising two windings
(a) & (b) wound on the same core.
(a) a shunt winding that is voltage (polarised) operated - used to monitor the
generator voltage & close its contacts when this is 0.2-1V greater than the battery
... in turn energising the Contactor (III) that connects the generator to
the power bus
(b) a series winding that is (polarised) current operated - used to monitor the
current flowing in/out of the generator circuit relative to the battery ... when
a reverse current of 10-25 amps flows (ie the battery is taking the load)
the relay contacts open ... in turn releasing the Contactor (III) that disconnects
the generator from the power bus
So essentially the generator is voltage controlled to bring it online & (negative)
current controlled to take it offline ... hence the differing engine / generator
speeds related to these operations ... c.38% online & c.34% offline.
> If you put a GROUND on this terminal "6" it will close yet another relay
> coil inside of the Combined Device and will REMOVE the generator feed
> voltage from the Polarization Relay thus making it INOPERATIVE!
> Remember, if you disable the PR relay, then of course you have also
> disabled the MAIN CONTACTOR Relay, and thus, no voltage from the
> generator will ever make it to the main aircraft bus. The ground on
> terminal "6" is usually controlled by the Generator Switch in the
> cockpit.
2 - the Cyrillic "6" terminal (western "B") will release Differential Relay II(a)
on the bench with a ground (reverse bias), but this input is designed in situ
to monitor the battery / generator output (depending on whether the generator
is offline / online).
3 - note that the Cyrillic "B" (western "V") terminal connected to the Coupling
Relay (I) is fed by 28V (not ground) from a 10A protection fuse via the Over
Voltage Unit / External Power Disconnect Relay contacts / Generator Switch control
line. None of these external devices are connected to the Cyrillic "6" terminal.
The purpose of the Coupling Relay (I) is to isolate the generator / voltage
control equipment from the power bus in the event of external power connection,
over voltage, negative polarity or fault conditions.
> If at any time the generator puts out too much voltage, in the realm of
> 31.5 volts or so (+/- 0.5 volt) then a circuit breaker will pop on the
> over/under voltage detection and protection unit
4 - the Over Voltage Unit (western AZP-A2) does just that ... under voltage is
controlled by the DMD-200D "Complex Apparatus", with reverse polarity protection
from relay IV. The AZP-A2 operates above 31-32V although it has a time delay
to it that's voltage dependent to prevent short term transients tripping the
device. So it can take 0.5 sec to trip up to 37V & 0.12 sec up to 60V ... note
that this device has no self-test capability so we have to assume it will work
when needed! Once tripped it has an external button to reset it.
Was fortunate on my -52 to have discovered (during annual checks) over the last
few years both a loose carbon pile regulator and loose connections inside the
DC Power relay box ... before these became a serious issue ... so certainly good
advice to keep a look out for these problems.
Regarding the short circuits you found on your regulator / wiring ... could you
share the info on which wires shorted (together or to earth?), as in conjunction
with the schematic I sent you this might help identify which specific connected
devices got zapped?
Also when you traced the voltage output from the generator were you able to see
this at the DMD-200D Cyrillic "B" terminal (Coupling Relay I) control input ...
as if this relay is not energised the generator will remain isolated from the
power bus. Presume you found & tested the 10A protection fuse too?
Cheers, Rob R.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p-180#95180
Message 10
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| Subject: | Re: White Paper on Russian Generator System |
Rob - if not previously bestowed upon you, a call sign of "Sparky" is
clearly befitting your excellent demonstrated expertise!
Dave
In a message dated 2/14/2007 8:21:15 PM Pacific Standard Time,
yak-list@robrowe.plus.com writes:
--> Yak-List message posted by: "Rob Rowe" <yak-list@robrowe.plus.com>
Hi Mark,
Great diagnostic posting!
>From the schematics ... a few points around the (western) DMD-200D "Complex
Apparatus" for discussion from your description.
1 - the Polarised Relay (II) is of a differential design, comprising two
windings (a) & (b) wound on the same core.
(a) a shunt winding that is voltage (polarised) operated - used to monitor
the generator voltage & close its contacts when this is 0.2-1V greater than
the battery ... in turn energising the Contactor (III) that connects the
generator to the power bus
(b) a series winding that is (polarised) current operated - used to monitor
the current flowing in/out of the generator circuit relative to the battery
... when a reverse current of 10-25 amps flows (ie the battery is taking the
load) the relay contacts open ... in turn releasing the Contactor (III) that
disconnects the generator from the power bus
So essentially the generator is voltage controlled to bring it online &
(negative) current controlled to take it offline ... hence the differing engine
/
generator speeds related to these operations ... c.38% online & c.34%
offline.
> If you put a GROUND on this terminal "6" it will close yet another relay
> coil inside of the Combined Device and will REMOVE the generator feed
> voltage from the Polarization Relay thus making it INOPERATIVE!
> Remember, if you disable the PR relay, then of course you have also
> disabled the MAIN CONTACTOR Relay, and thus, no voltage from the
> generator will ever make it to the main aircraft bus. The ground on
> terminal "6" is usually controlled by the Generator Switch in the
> cockpit.
2 - the Cyrillic "6" terminal (western "B") will release Differential Relay
II(a) on the bench with a ground (reverse bias), but this input is designed
in situ to monitor the battery / generator output (depending on whether the
generator is offline / online).
3 - note that the Cyrillic "B" (western "V") terminal connected to the
Coupling Relay (I) is fed by 28V (not ground) from a 10A protection fuse via the
Over Voltage Unit / External Power Disconnect Relay contacts / Generator
Switch control line. None of these external devices are connected to the Cyrillic
"6" terminal. The purpose of the Coupling Relay (I) is to isolate the
generator / voltage control equipment from the power bus in the event of external
power connection, over voltage, negative polarity or fault conditions.
> If at any time the generator puts out too much voltage, in the realm of
> 31.5 volts or so (+/- 0.5 volt) then a circuit breaker will pop on the
> over/under voltage detection and protection unit
4 - the Over Voltage Unit (western AZP-A2) does just that ... under voltage
is controlled by the DMD-200D "Complex Apparatus", with reverse polarity
protection from relay IV. The AZP-A2 operates above 31-32V although it has a time
delay to it that's voltage dependent to prevent short term transients
tripping the device. So it can take 0.5 sec to trip up to 37V & 0.12 sec up to
60V
... note that this device has no self-test capability so we have to assume it
will work when needed! Once tripped it has an external button to reset it.
Was fortunate on my -52 to have discovered (during annual checks) over the
last few years both a loose carbon pile regulator and loose connections inside
the DC Power relay box ... before these became a serious issue ... so
certainly good advice to keep a look out for these problems.
Regarding the short circuits you found on your regulator / wiring ... could
you share the info on which wires shorted (together or to earth?), as in
conjunction with the schematic I sent you this might help identify which specific
connected devices got zapped?
Also when you traced the voltage output from the generator were you able to
see this at the DMD-200D Cyrillic "B" terminal (Coupling Relay I) control
input ... as if this relay is not energised the generator will remain isolated
from the power bus. Presume you found & tested the 10A protection fuse too?
Cheers, Rob R.
Message 11
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| Subject: | White Paper on Russian Generator System |
What a great job, Mark, THANKS A LOT! This will help me solve the Voltage
Regulation problems in my Yak 50 !
Jan Mevis
RA2005K
-----Original Message-----
From: owner-yak-list-server@matronics.com
[mailto:owner-yak-list-server@matronics.com] On Behalf Of Bitterlich, Mark G
CIV Det Cherry Point, MALS-14 64E
Sent: woensdag 14 februari 2007 23:15
Subject: Yak-List: White Paper on Russian Generator System
MALS-14 64E" <mark.bitterlich@navy.mil>
YAK-50 DC Power Generation and Troubleshooting by Mark Bitterlich N50YK
Warning: This is a technical explanation of the power generation,
regulation, and connection to aircraft main's of the typical
Yak-50/52/55 or Sukhoi-26/29/31. It is offered for those that have at
least a general understanding of electronics. In all cases where
voltage from power supplies or from batteries were connected for
testing, circuit breakers were installed for safety. If anyone tries to
follow these notes and duplicate my efforts, beware... if you make
mistakes, or fail to include current limiting devices such as light
bulbs and circuit breakers/fuses, you could easily cause serious damage
to aircraft wiring. Ok.. so I had to cover my six. That said, let's
move on.
I just spent the last few days learning my YAK-50's electrical power
generation system. Thanks for all of those that sent schematics of what
you had on hand. Every person contributed towards solving this puzzle!
THANKS TO EVERYONE! The specifics in some regards focus on the YAK-50,
although all of the Yak's and Sukhoi's use close to the same design with
some slight wiring differences here and there. The important thing is
that in most cases the parts are all identical. Of course this does not
include "Westernized" designs, such as the 52W, 52TW, etc. Most of
these have already had B&C (or other) products installed.
Power generation starts with the generator. This is a 3 KW monster that
is capable of 100 amps output if properly cooled. This same generator
can operate at 30 amps intermittent duty with no cooling air.
There are 3 wires on the generator, + positive, - negative, and what the
Russians refer to as "Shunting Input". This input is actually what
controls the generator output and is normally called "Field Excitation".
This generator has a very well designed voltage regulation system using
a carbon pile voltage regulator that controls field voltage within a +2
/ -2 volt range. Voltage output is also stabilized with a bucking
transformer known in Russian as "The Stabilizing Transformer". If you
want to see examples of systems like this, go back to WW-II designs and
you will see the exact same thing. In other words, this is 60 year old
technology and you need to go back and read about some of the theory
involved, because like a bucking transformer, you rarely see these
components in today's designs, but they were very common before the
discovery of high current voltage regulation transistors.
Basically, most of the system is self starting and self contained
regulating in a closed loop circuit. As soon as the generator starts
spinning, it will put out voltage although at idle it will be much lower
than 28 volts and it will not be connected into the aircraft mains. As
RPM comes up and voltage rises, it will eventually stabilize at the
rated voltage set by the carbon pile regulator. So, if you have any
kind of problem, the first thing you will want to do is to gain access
to the main generator terminals (you have to remove a cover on the
generator) and hook a meter to the PLUS and MINUS connectors with LONG
meter leads so that you can then safely check the voltage when you start
the engine. If your generator is putting out voltage at idle, give it a
quick boost to about 60% or so, and you should see your meter come up to
around 28 voltage (plus or minus a few tenths) and then start
regulating. By "starting to regulate", I mean that the voltage will stop
increasing as you continue to raise engine RPM If you have NO output
voltage, shut the engine off, and then when you are eyeballing the
inside of the generator, slowly move the prop. Does the generator spin?
If so, then that is a good thing. If NOT, then you have sheared a shaft,
replace the generator. If it does rotate, start it back up and run a
test for Field Excitation Voltage. If you have excitation voltage, then
again it is probably a bad generator. If you have no excitation, there
are a few other things that could be wrong, such as the carbon pile
regulator itself, or your over voltage breaker has tripped.
If at any time the generator puts out too much voltage, in the realm of
31.5 volts or so (+/- 0.5 volt) then a circuit breaker will pop on the
over/under voltage detection and protection unit. This is a silver box
with two cannon plugs on it, that is in the nose inspection hole left
side top in the 50, and somewhere else in the 52. I think it is in the
forward cockpit underneath the instrument panel on the 52 but don't
quote me. This unit has a rubber covered breaker button that you can
reach in and reset if you have had an over-voltage condition. It is
another thing to check anytime you have a problem, but typically an
over-voltage trip is not common.
Moving on, the closed loop design has generator output going first to
the stabilization transformer primary winding, then through that
directly to a component called "The Combined Device" also known as the
DMR-200D. This component (the DMR-200D) is located in the gray box
mounted on the firewall, top right side (looking forward) in the 50, and
by the Pilots right foot in the 52. Power goes through a MAIN CONTACTOR
RELAY inside of the Combined Device ONLY IF CERTAIN CONDITIONS ARE MET.
Here is where things get tricky.
Going back the Stabilizing Transformer for a minute, (just to complete
the mental image) main output voltage of the generator goes through the
primary winding as I already mentioned. This is just a few turns of
wire, and offers VERY little resistance. Part of the secondary windings
of this transformer system has outputs going to the voltage regulator
and the over voltage box. The Voltage Regulator (official name "R-27")
has outputs that feed back to control the generator excitation field,
but it also has another output that goes over to the over voltage box.
If the voltage is normal, the over voltage box feeds this same voltage
(28 volts) back to pin B on the Combined Device. (Note, it looks like a
"B" to me, that is the SHAPE of the marking, but it is actually the
Russian letter "V".) This input voltage to pin B (V in Russian) turns
on internal relay TKE-210B INSIDE of the Combined Unit. The
nomenclature of this relay means nothing since you can't see or touch it
without taking the whole thing apart. Just realize that when you put 28
volts to the connection marked "B" and a ground on the connection marked
"-" (for minus), an internal relay will close and it will ENABLE the
rest of the Combined Device. When this first relay closes, it then
enables yet another system inside of the Combined Device known as the
Polarization Relay. The "PR" is a special dual winding relay that will
close only if current flows through the relay coil itself in the proper
direction. If you try to flow current through this relay backwards, it
simply won't work, and that is by design. It is SUPPOSED to do that.
After the Polarization Relay (or PR) is enabled, it has a circuit that
connects it to both the output main terminal and the input main
terminal. If the PR likes what it sees and closes, it then in turn
provides power for yet ANOTHER Relay Coil inside of the Combined Unit,
this one is known as the MAIN POWER CONTACTOR RELAY. This is the big
boss relay in the whole thing, and when it closes, generator power then
comes OUT of the Combined Unit and is fed to the aircraft MAIN BUS BAR.
In other words, the MAIN POWER CONTACTOR actually connects the large
input terminal to the large output terminal on the Combined Unit.
What is really tricky to understand about this whole design is the
Polarization Relay. Consider this: When you turn on the Aircraft
Master, Battery Voltage is fed to the MAIN BUS and as such it also is
fed right down to the large OUTPUT terminal of the Combined Unit. At
this point, the OUTPUT of the Combined Unit is not connected to
ANYTHING, because the MAIN CONTACTOR RELAY is still OPEN. Let's
consider our battery voltage to be a normal. As such, there is about 24
volts on the Combined Units OUTPUT terminal post coming from the battery
with the Aircraft Master switch turned on.
Now let's start the engine. The generator starts to spin. Everything
works properly and as your engine speed comes up, so does generator
voltage. This voltage is now fed to the Combined Unit's INPUT power
terminal. Assuming 28 volts is fed to terminal "B" ("V" in Russian)
thus ENABLING the Combined Unit, you will end up with battery voltage on
one side of the Polarization Relay Coil and Generator Voltage on the
OTHER side of the Polarization Relay Coil. Once there is a difference
in voltage between battery voltage and generator voltage of about 2
volts or so, and the generator voltage is HIGHER than the battery
voltage, the Polarization Relay will CLOSE and will then in turn close
the MAIN POWER CONTACTOR. Once the MAIN POWER CONTACTOR is closed, 28
volts will be fed out terminal "C" which will then in turn close yet
another relay (external to the Combined Device) and turn OFF the
Generator Light in the cockpit. It also then of course is feeding
generator power directly to the aircraft main power bus.
Not done yet! There is yet ANOTHER relay coil in the Combined Device
that is only enabled if the main enabling relay is powered up through
terminal "B" as mentioned earlier. If terminal B has 28 volts, then
terminal "6" becomes active (In Russian the "6" is actually the Russian
letter "B"... confused yet? Easy to do. Just remember that as I write
this, I refer to how they look to me and how they will look to YOU!) If
you put a GROUND on this terminal "6" it will close yet another relay
coil inside of the Combined Device and will REMOVE the generator feed
voltage from the Polarization Relay thus making it INOPERATIVE!
Remember, if you disable the PR relay, then of course you have also
disabled the MAIN CONTACTOR Relay, and thus, no voltage from the
generator will ever make it to the main aircraft bus. The ground on
terminal "6" is usually controlled by the Generator Switch in the
cockpit. And here is a warning... not all Russian designs work like
this. From the Sukhoi to the Yak there are major wiring differences in
how they wire this device, but the general concepts are the same.
Operationally testing a system like this can be difficult at best. I
tried a method that worked for me, but is offered with a Caveat Emptor
warning... buyer beware, your mileage may vary and if you smoke you
whole aircrafts electrical system, DO NOT blame me.
I disconnected all three leads from the generator. I used a small 10
watt 28 VDC light bulb connected to the field winding wire to ground. I
took the main generator PLUS and MINUS wires off of the generator and
hooked them to a 28 volt variable DC power supply of about 20 amps
capacity. DO NOT LEAVE ANY OF THE AIRCRAFTS WIRES CONNECTED TO THE
GENERATOR. The Field Winding can either float or have a SMALL 28 volt
DC light bulb hooked from it to ground.
You can now bring up voltage with the variable supply and check for
voltages at proper locations without having to run the M-14 engine
itself. Initially set the variable supply to about 20 volts. Look for
this 20 volts from the variable power supply at Combined Device Input
terminal. (Right side bottom.. the BIG one). Turn on the Aircraft
Master and look for BATTERY voltage on the OUTPUT terminal (left side
middle of the Combined Device...the OTHER big one) Look for 20 volts on
terminal "B" and NO GROUND on terminal "6". Increase voltage on the
variable supply to 28.0 volts even. As you come up on the voltage, the
MAIN CONTACTOR should close with a loud WHACK. If not, you have
problems with the Combined Device.
Remove the Combined Device and bench check it. Here is how you go about
doing that.
Some of the internal relays can be checked simply by listening to them
click. No, this does not check the relay CONTACTS themselves, but hey,
that comes later. Using a 28 volt source, either battery or variable
supply, connect negative to the (-) terminal on the Combined Device.
Connect 28 volts to terminal B. You should hear a relay click.
Disconnect from B. Now connect 28 volts to terminal A..(It looks sort
of like an A anyway) It is on the right side above the large INPUT
terminal. You should hear a LOUD relay closing, this is the main
contactor. Remove power from "A". Reapply power to "B"... again you
hear a relay click. Leaving power applied to B, now hook a grounded
wire to pin 6. This will close ANOTHER relay and you should be able to
hear it click. You have now checked every relay coil in the Combined
Device, other than the Polarization Relay, and the internal relay
contacts themselves.
Find a 24 volt battery, or hook two 12 volt batteries in series. Hook
the negative lead of the battery to the negative side of your variable
power supply. Also connect a wire from this to the MINUS (-) terminal
on the Combined Device. So all negatives (grounds/earths) are now
common to each other. Hook the plus lead of the battery to the OUTPUT
side of the Combined Device (Big terminal left side middle).
Variable power supply is now OFF.
Apply a wire from the 28 volt variable supply output (plus voltage) to
the MAIN INPUT terminal (bottom right side). Also connect a jumper from
this terminal to terminal "B". Put some voltmeters here and there to
monitor whatever you feel like, but most certainly variable power supply
output voltage. Increase the variable power supply output. When it
reaches about 2 volts or so MORE than the battery voltage, the MAIN
CONTACTOR will close, and you will now have connected your variable
power supply to your test batteries.... and remember, when you do this,
you have just created a battery charger, and the variable power supply
will now try to start charging the batteries! If your variable power
supply is too small, as soon as it starts to try and charge the
batteries through the now closed MAIN CONTACTOR RELAY, the variable
power supply voltage will DROP. This will trigger the Polarization
Relay to OPEN, then causing the MAIN CONTACTOR to open as well, and
battery charging will cease... at which point the variable power supply
will jump back up in voltage, the polarization relay will close again
and the whole cycle will repeat. This event happens very fast and will
make a lot of noise. So... warning... use a variable power supply that
can handle more than a few amps without voltage drop for this test. A
regulated supply that is variable as well would be ideal.
Ok, so what if the MAIN CONTACTOR does NOT energize when you increase
the voltage? More than likely, you have problems with the Polarization
Relay. This device seems to wear out first, and the word has it that you
can take this Combined Device apart and adjust these contacts to fix
this relay. I have not done that yet, but am getting ready to.
The Combined Device is a rather rare animal and sooner or later is going
to give us all a certain amount of grief. Without a doubt, I suspect if
we continue to fly these aircraft we are going to have to get more of
these devices at a reasonable cost, or build our own, or convert the
whole aircraft power generation system over to American made. The
latter is probably the best idea over the long run.
So there you have it. The methods for testing this system are my own
and not adopted from any other manual or article. Use them at your own
risk. Feel free to copy and distribute this article as you see fit, but
I would sincerely appreciate it if you left my name on it as the author.
Addendum:
Every Russian aircraft owner should take a careful look at the Carbon
Pile Voltage Regulator R-27. Vladimir Yastremski warned me about this
device, and his warning was dead on accurate. This device is mounted on
a very very loose shock mount and rocks and rolls all over the place in
flight. It has wires that screw onto terminals and as the thing moves,
it can cause a short circuit to certain terminals. Sure enough, on my
YAK-50, one of the terminals was blackened by a short circuit. As I
moved the whole thing around, I could see how it caused the short.
Second, look at all the wiring that goes anywhere near bulkheads and/or
"bulb angle". It is common to see chaffing here, and sure enough... I
had another wire burnt almost in two by short circuits in THIS area.
So, bottom line, 50 owners... save yourself a lot of grief and get you
head up into that nose equipment compartment and inspect all wiring
CAREFULLY!!!
Best of Luck to all who decide to fix problems with this system on their
own... it's not easy, but this article should help you get started at
least.
Mark Bitterlich
N50YK
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| Subject: | Re: White Paper on Russian Generator System |
In a message dated 2/14/2007 9:29:13 PM Pacific Standard Time,
KingCJ6@aol.com writes:
Rob - if not previously bestowed upon you, a call sign of "Sparky" is clearly
befitting your excellent demonstrated expertise!
Nope,Dave. Sorry, "Sparky" already belongs to Doug Sapp's lovely daughter.
I'll go for "Sparks", though. ...Blitz, Chairman
AHSACSC
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