Today's Message Index:
----------------------
1. 12:12 AM - Re: Fw: Hello everyone , new here and need some help ! (Neil Parkinson)
2. 05:52 AM - Re: What to monitor in a dual alternator airplane (Robert L. Nuckolls, III)
3. 08:38 AM - Re: What to monitor in a dual alternator airplane (Robert L. Nuckolls, III)
4. 08:45 AM - Re: Fw: Hello everyone , new here and need some help ! (Robert L. Nuckolls, III)
5. 09:26 AM - Z-13/8 OPS (CORRECTION) (Robert L. Nuckolls, III)
6. 09:57 AM - Re: What to monitor in a dual alternator airplane (argoldman@aol.com)
7. 03:10 PM - Re: What to monitor in a dual alternator airplane (Robert L. Nuckolls, III)
Message 1
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Subject: | Re: Fwd: Hello everyone , new here and need some |
help !
Thank you Bob.
It=99s great to have access to your thoughts. With your recommended ac
tions below following a main alt failure, does this mean you recommend opera
ting with the Aux Alt always turned on ? Or is this turned on in addition to
selecting DC PWR Off and E-Bus Alt feed.
Out of interest what is the SD-8 output doing when the Aux Alt relay is ope
n ? Does it produce a steady 12 , or float around if I was measuring it ?
Thanks again !
Neil
> On 24 Sep 2018, at 03:10, Robert L. Nuckolls, III <nuckolls.bob@aeroelectr
ic.com> wrote:
>
>> Im building an Rv8 and would like to make it IFR with a Garmin g3x fit .
>>
>>
>> After reading the excellent online book Aeroelectric Connection i intend t
o use the system 13/8 with B&C parts . (Attached Diagram )
>>
>> I however have a few questions , as my school boy electrics is strugglin
g !
>>
>>
>> 1)What happens to an Alternator ( in this case the SD-8) when it reaches i
ts max current capacity , does it get hot and eventually blow , or does it j
ust start decreasing its voltage output , eventually going below the battery
voltage causing a current drain from the Batt ?
>>
>> Yes . . . the bus simply sags until the
>> battery picks up the slack. Nothing smokes.
>> BUT . . . you should configure your ENDURANCE
>> loads to remain at or just below the maximum
>> output of the SD8 which is on the order of
>> 10A. This is your en route configuration.
>>
>> Then, when it's time for descent and approach
>> to landing, you can turn on all the goodies
>> and use SD8+battery to complete the flight.
>>
>> This holds ship's battery energy in reserve
>>
>>
>> 2) If its the former I'm thinking following a Main Alternator failure if
the Aux Alternator is turned on ( without opening the main battery contact
or ) maybe there is room to overload this too ? If so i was thinking maybe a
n improvement to this system would be an interlock that when the E-Bus and A
ux Alt are activated they open the ground to the battery contactor coil an
d thus prevent an overload of the emergency system ? Maybe you could have a g
uarded 3 posn switch that on first click , opens the main battery contactor a
nd closes the E-Bus Alternate feed , then second click closes the AUX - Alt f
eed relay ? A one switch saves the day sort of thing ??
>>
>> Why so much monkey-motion? If the main alterantor
>> fails you get a low volts warning whereupon you
>> finish your cup of coffee before configuring
>> to endurance mode by:
>>
>> E-Bus alt feed closed
>>
>> DC PWR master OFF
>>
>> Reduce loads on E-bus to 10A or less
>> if needed.
>>
>> On descent and approach, delay bringing
>> any other electro-whizzies on for as long
>> as practical, then move DC PWR master to
>> BAT and continue normal ops to the
>> runway.
>>
>> 3) It would be nice to have a CAS message on my Garmin G3x that indicates
if the SD-8 is functioning ok incase of a main failure . Im thinking of a
=9CStandby Alt Fail =9C caption that would indicate when ever the S
D-8 is not producing power and ready for an emergency . What sort of output w
ould an unloaded ( Supply relay open ) Sd-8 be producing ? unstable , high ,
low or on task at 12v?? How can i send a =9CI'm functioning ok and pr
oducing power =9C signal ? Maybe a relay coil on its output that close
s a signal to the G3X ?? ( see my hand drawing )
>>
>> But maybe id need diode after that coil to ensure its only Aux Alt that c
an close it and not reverse supply ?? What would a Diode in the line do to s
upply voltage ?? How could i make it so the relay closes at 12ish volts ??
>>
>>
>> Any better ideas ??
>>
>>
>> Too many questions I know !
>>
>>
>> Thank you so much for any help !
>>
>> Z13/8 is about the most reliable system
>> flying in light aircraft today. It's light,
>> low cost, has an excellent FMEA outcome
>> and no downstream periodic/preventative
>> maintenance for continued airworthiness.
>>
>> If the G3X has a low voltage annunciation
>> feature, program it for about 13.0 volts.
>> That's all you need.
>
> Bob . . .
Message 2
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Subject: | Re: What to monitor in a dual alternator airplane |
At 09:50 PM 9/23/2018, you wrote:
>Folks,
>
>Over the years that I subscribed to this mailing list, there have
>been many conversations about monitoring voltage and current in an
>airplane. I want to approach this from a different perspective and
>see if I understand correctly.
>
>The basic questions are:
> * What should I monitor in my airplane?
> * How do I interpret the indications, especially in flight?
Bus voltage with ACTIVE NOTIFICATION of
LOW VOLTS.
LIGHT OFF, pour another cup of coffee.
LIGHT ON, finish present cup of coffee . . . turn
ON E-bus alternate feed, turn OFF battery master.
If you have a second alternator, turn it ON but
reduce e-bus loads to that which the alternator
supports.
AIRPORT IN SIGHT, turn battery master back on
and terminate flight.
Just because you CAN monitor a lot off stuff
doesn't mean that it's useful for managing
systems during flight. In fact, being able
to take a video game tour through your electrical
system is a DISTRACTION from your duties as
pilot. Be a pilot in the air and a mechanic
on the ground.
>My own airplane has a 12 volt system with two B&C alternators and
>voltage regulators. The primary regulator is an LR3C preset to 14.4
>volts. The standby regulator is part of an SB1B-14 and is preset to 13.0 volts.
13.5 is better based on the analysis offered
yesterday.
>Here is what I think that I need to monitor:
> * Voltage (should pretty pretty much the same everywhere so I am
> just using my EFIS' bus voltage indicator)
Yup, you can stop there . . . everything else is
superfluous to your comfortable termination of the
flight. Save those machinations as to cause/effect
until on the ground . . . especially when the troops
here on the List are available to help.
Bob . . .
Message 3
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Subject: | Re: What to monitor in a dual alternator airplane |
>Barry - Why would you have the second Alt. set to ANYTHING less than
>the charging voltage?
>13.0 VDC is NOT a Charging Voltage.
Correct. There are TWO choices in the B&C product
line for selection of an AUX alternator controller.
The SB/LS series regulators were tailored for Z-12
style installations in TC aircraft where the AUX
alternator is paralleled to the main bus and turned
ON during normal phases of flight. The AUX controller
is set for come level slightly below the MAIN
controller so that under normal ops, it completely
relaxes but in a condition ready to go to work
should the bus voltage drop.
The AUX alternator was never intended to charge
batteries . . . only hold the bus at some level
above the battery's discharge voltage such that
battery energy is held in reserve for decent/approach
phases of flight.
If the bus voltage drops below the AUX controller
set point, the AUX alternator wakes up and a SPECIAL
circuity within the controller senses this and illuminates
an ALTERNATOR LOADED light.
The stand-by versions of the alternator controller
are not recommended for simple dual alternator installations
where the auto-switch feature is not necessary . . .
this was a 'bell-n-whistle' aimed primarily at the
STC market for TC aircraft that were receiving the
pad driven, aux alternators.
Yeah, 13.0 is a bit too low . . . 13.5 is better.
Will talk with B&C about this. Further, if one is
flying a lithium battery, the set-point for the
SB/LS regulators becomes still more critical.
There will probably be a reassessment of design
philosophy for alternator controllers to bring
them into better alignment with the new
technologies.
. . . but know that there is a reason for
the '13.0 madness' . . .
Bottom line is that there is no good reason
to monitor/worry/fuss over any condition other
that to know that bus voltage is above 14.0V. It can
never be that high except that the alternator
is carrying present system loads. If that
condition changes, then you call in the cavalry
and bring the bus back up to 13.5 or higher
depending on the second system installed.
ALL other currents, voltages, humidity and
phases of the moon are irrelevant to the primary
goal of supporting needed electro-whizzies
through all phases of the flight.
Bob . . .
Message 4
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Subject: | Re: Fwd: Hello everyone , new here and need some |
help !
At 02:11 AM 9/24/2018, you wrote:
>Thank you Bob.
>
>It=99s great to have access to your thoughts.
>With your recommended actions below following a
>main alt failure, does this mean you recommend
>operating with the Aux Alt always turned on ? Or
>is this turned on in addition to selecting DC PWR Off and E-Bus Alt feed.
Z-13/8
Pre Engine Start:
E-BUS Alt Feed . . CLOSE for ATIS/Clearance
then . . OPEN
Normal ops: DC PWR master . . . BAT + ALT
AUX alternator . . OFF
E-BUS Alt Feed . . OPEN
On presentation of LV warning:
DC PWR master . . . OFF until airport in sight
AUX alternator . . ON
E-BUS Alt Feed . . CLOSED
E-Bus Loads . . . . reduce as needed
Airport in sight:
DC PWR master . . . BAT only
>Out of interest what is the SD-8 output doing
>when the Aux Alt relay is open ? Does it produce
>a steady 12 , or float around if I was measuring it ?
14.0 plus or minus . . . it's not loaded
so the regulator is a bit sloppy until the
relay is closed to hook it to the battery.
Bob . . .
Message 5
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Subject: | Z-13/8 OPS (CORRECTION) |
> Z-13/8
>
> Pre Engine Start:
>
> E-BUS Alt Feed . . CLOSE for ATIS/Clearance
> then . . OPEN
>
> Normal ops: DC PWR master . . . BAT + ALT
> AUX alternator . . OFF
> E-BUS Alt Feed . . OPEN
>
> On presentation of LV warning: (HAD SOME SWITCHES IN WRONG SEQUENCE)
>
> AUX alternator . . ON
> E-BUS Alt Feed . . CLOSED
> DC PWR master . . . OFF until airport in sight
> E-Bus Loads . . . . reduce as needed
>
> Airport in sight:
>
> DC PWR master . . . BAT only
Bob . . .
Message 6
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Subject: | Re: What to monitor in a dual alternator airplane |
Art,
=C2-
It depends on what the purpose of the second alternator is. If it is a stan
dby in case of primary alternator failure then you want the secondary to be
on line when the voltage of the bus goes down a certain amount indicating
either excessive draw or primary alternator failure.
=C2-
If you have both set at the same voltage, they are both theoretically opera
ting and you will not be able to tell if one fails. Set the way as suggeste
d in this post,all you have to do as a pre-check is to alternately check th
e voltage each puts out at run-up. Further checking is unnecessary as if th
e bus voltage is lower than what you expect from the primary and is staying
constant, you have a primary alternator failure. If it is lower than prima
ry expectation and continues to decline you probably have failure of primar
y and secondary alternators.
=C2-
Rich
=C2-
In a message dated 9/23/2018 11:09:11 PM Central Standard Time, flyadive@gm
ail.com writes:
=C2-
Art:
=C2-
=C2-
On Sun, Sep 23, 2018 at 10:55 PM Art Zemon <art@zemon.name> wrote:
Folks,
=C2-
Over the years that I subscribed to this mailing list, there have been many
conversations about monitoring voltage and current in an airplane. I want
to approach this from a different perspective and see if I understand corre
ctly.
=C2-
The basic questions are:
What should I monitor in my airplane?How do I interpret the indications, es
pecially in flight?My own airplane has a 12 volt system with two B&C altern
ators and voltage regulators. The primary regulator is an LR3C preset to 14
.4 volts. The standby regulator is part of an SB1B-14 and is preset to 13.0
volts.=C2-
Barry - Why would you have the second Alt. set=C2- to ANYTHING less than
the charging voltage?
13.0 VDC is NOT a Charging Voltage.=C2- Minimum Charging Voltage=C2-is
13.8 VDC with a Max around 14.5 VDC.=C2- For some reason people can not a
gree on the Max. Voltage.=C2- It is usually 14.2 to 14.5 VDC.=C2-
=C2-
Here is what I think that I need to monitor:
Voltage (should pretty pretty much the same everywhere so I am just using m
y EFIS' bus voltage indicator)Current (I strapped a solid state current sen
sor to the wire going from the master contactor to the fuse block)Primary r
egulator overvoltage indicatorStandby regulator overvoltage indicatorPrimar
y regulator/alternator ON (physical switch turned on)Standby regulator/alte
rnator ON (physical switch turned on)And here is how I think I should inter
pret stuff:
Voltage approximately 14.4 volts: Everything is happy with the primary alte
rnator and regulator doing their things.Voltage approximately 13.0 volts: M
y primary alternator isn't providing power or my primary regulator isn't wo
rking properly. Barry - =C2-Forget about the 13.0 VDC.=C2- It is too lo
w.=C2- And only shows the output of your #2 Alt is not sufficient to char
ge a battery.
If you see BATTERY VOLTAGE anything around 12.5 VDC or Less you are running
=C2- on battery and that is not good.
=C2-
Check that the primary alternator switch is turned on. If the standby regul
ator does not have an overvoltage indication then it is operating normally
and I do not have a flight urgency.Barry - What is "normal" if=C2- you ar
e NOT putting out a voltage that will charge the battery?=C2-=C2-
You are already below normal.
An idiot light is a back-up to a volt meter.=C2- If =C2-the bulb goes i
n the idiot light you are relying on something that will=C2- never work.
If the volt meter shows a failure you KNOW there is something wrong and cro
ss check to the idiot light.=C2-
BUT!=C2- That is ONLY for a LOW voltage.=C2- What about OVER VOLTAGE?
If the volt meter failed and NOW it is time to check=C2- if the Idiot lig
ht=C2- says the same thing.
Voltage lower than 13.0 volts: I have problems with both regulators/alterna
tors and I am depleting the battery. This needs attention.If the voltage is
lower than 13.0 volts, check that the alternator switches are turned on. I
f both are turned on and voltage is still low, check the current draw. At c
ruise RPM, I can expect 30 amps from the standby alternator.Barry - Not cor
rect!=C2- The Alt Systems has the ability to SUPPLY 30 Amps.=C2- BUT!
=C2- That is ONLY if the Load on the plane is 30 Amps.
I need to intelligently balance load and amps available (governed by engin
e RPM) against battery capacity and remaining flight duration.Barry - You d
o not have to balance anything.=C2- That is the job of ACU's.
What you should have done during designing and building your plane is:
Figure out ALL your electrical equipment draw and add a bit for future expa
nsion AND THEN pick a Primary Alt that can supply 20% Greater than the Full
Load.
Voltage higher than 14.4 volts: The overvoltage protection in the primary r
egulator has failed. Turn off the primary alternator.Barry - YES!=C2- But
, don't stop there.=C2- What if the over-voltage condition is coming from
the back-up Alt?
=C2-
Side Note:=C2- It is standard practice to crosscheck against at least two
instruments.=C2-
=C2-
Barry
=C2-
"If you wash your hands before you go to the bathroom you might have the ma
king of a crew chief."
=C2-
=C2-
Do I have it right?
=C2-
=C2- =C2- -- Art Z.
--
https://CheerfulCurmudgeon.com/
"We do not see the world as it is. We see the world as we are."
Message 7
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Subject: | Re: What to monitor in a dual alternator airplane |
>If you have both set at the same voltage, they are both theoretically
>operating and you will not be able to tell if one fails.
Which is why simultaneous operation of two alternators
has never been recommended in the 'Connection.
I designed a regulator for the Cessna 303 to parallel
two alternators but it was fussy and they abandoned
the idea in favor of the single regulator driving
two alternators idea used on the 336/337 series
aircraft.
By operating only one at a time, failure of the active
alternator is immediately annunciated by the LOW VOLTS
warning light whereupon crew positioning of a few switches
mitigates the condition.
Except for starter-generators on turbine twins, we
almost never run two engine driven power sources
to the same bus. Z-14 is an example of dual alternator/
dual battery system that purposefully separates
them into independently operated systems that
can share energy under certain circumstances:
One alternator failed and during engine cranking.
All other times, it's better to have them separate
with active notification of low volts for each
system.
Simpler, less expensive and much better FMEA
outcome.
Bob . . .
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