Today's Message Index:
----------------------
1. 04:43 AM - CROWBARS? (bobnoffs)
2. 05:08 AM - Re: Re: Z-* Question (C&K)
3. 05:36 AM - Re: Z-* Question (user9253)
4. 07:26 AM - Re: Re: Z-* Question (Robert L. Nuckolls, III)
5. 07:38 AM - Re: Re: Z-* Question (Kelly McMullen)
6. 07:54 AM - Re: CROWBARS? (Robert L. Nuckolls, III)
7. 08:01 AM - Re: Re: Z-* Question (Ken Ryan)
8. 08:18 AM - Re: Z-* Question (BMC_Dave)
9. 08:34 AM - Re: Z-* Question (BMC_Dave)
10. 08:44 AM - Re: CROWBARS? (Charlie England)
11. 09:33 AM - Making your own fuseable links (JOHN TIPTON)
12. 10:04 AM - Re: Re: Z-* Question (Ken Ryan)
13. 10:35 AM - Re: Z-* Question (user9253)
14. 10:55 AM - Re: Z-* Question (BMC_Dave)
15. 11:21 AM - Re: Re: Z-* Question (Sebastien)
16. 11:32 AM - Re: Z-* Question (Rocketman1988)
17. 11:33 AM - Re: Making your own fuseable links (Robert L. Nuckolls, III)
18. 11:40 AM - Re: Re: Z-* Question (Robert L. Nuckolls, III)
19. 11:42 AM - Re: Z-* Question (BMC_Dave)
20. 11:45 AM - Re: Re: Z-* Question (Robert L. Nuckolls, III)
21. 11:47 AM - Re: Z-* Question (BMC_Dave)
22. 12:09 PM - Re: Re: Z-* Question (Sebastien)
23. 12:25 PM - Re: Re: Z-* Question (C&K)
24. 12:28 PM - Re: Z-* Question (BMC_Dave)
25. 12:28 PM - Re: Re: Z-* Question (Robert L. Nuckolls, III)
26. 12:40 PM - Re: Z-* Question (user9253)
27. 12:43 PM - Re: Z-* Question (Rocketman1988)
28. 01:01 PM - Re: Z-* Question (BMC_Dave)
29. 01:04 PM - Re: Z-* Question (BMC_Dave)
30. 03:37 PM - Re: Re: Z-* Question (Charlie England)
31. 04:10 PM - Re: Re: Z-* Question (Robert L. Nuckolls, III)
32. 08:55 PM - Re: CROWBARS? (James Kale)
Message 1
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hi all,
in the past a crowbar would stop the current from an overvoltage source quick
enough to prevent avionics damage.
is that really needed any more?
i have a honda [viking] engine with auto accessories. i don't hear of cars blowing
out their glass dashboards.
when i asked b and c about a 'crowbar' they said theirs was only recommended for
a permanent magnet alternator.
what are others doing with auto alternators?
thanks
bob noffs
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=481549#481549
Message 2
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| Subject: | Re: Z-* Question |
>I don't see anything on the architecture drawing that would warn you
that the main battery bus has been disconnected from the alternator(s)
Dave
I think this thread is a worthwhile discussion but I'm not sure exactly
where our miscommunication is.
I had assumed that we all agreed that it was essential to add a means of
incorporating immediate notification if the battery is not charging for
an EFI engine.
To me that means monitoring of the battery buss if the battery buss is
powering the EFI.
There are several ways of doing that over and above anything shown on a
Z figure. But all the low voltage warning devices are expected to
activate when the voltage drops below about 13.5 volts which will happen
as soon as the alternator goes offline.
Don't know if it is a factor for this conversation but folks flying with
a carb, mags, and vacuum instruments will think of low voltage warning
as being important for the avionics buss especially if IFR. Folks with
an electrically dependent engine like me will contend that it is more
important to monitor the battery buss directly. Most of the electrically
dependent engines that I've seen so far are automotive conversions that
often are VFR only so again the battery buss tends to be the important
thing to monitor.
Ken
Message 3
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| Subject: | Re: Z-* Question |
Chances are that a failed battery contactor will result in unstable alternator
output voltage that will set off an alarm in the EFIS.
If a failed battery contactor is such a big concern, why not put a relay in parallel
with it?
If low battery voltage is a concern, why not install a voltmeter or low voltage
warning?
The chances of making a forced landing for some reason are much greater than a
battery contactor failing in flight. Wouldn't it be better to have the ability
to shut off all electrical power at the source to minimize the chances of a
a spark igniting leaking fuel?
If there is smoke in the cockpit, it is desired to be able to shut off all electrical
power at the source. Keep always-hot wires as short as possible.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=481552#481552
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| Subject: | Re: Z-* Question |
>
>
>On Z14P, if the battery contactor opens then anything on the main
>battery bus will run until the 17AH main battery dies, right? If you
>have things like say, an electronic ignition, or electric fuel pump,
>that are required for flight you'd chug along completely unaware of
>the disconnect until your engine died, correct?
Yes . . . unless you put low voltage monitoring
on the battery . . . easy to do. But if engine
dependency on fuel pressure and ignition is
addressed by redundant systems, why are they
all running from one battery?
Bob . . .
Message 5
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| Subject: | Re: Z-* Question |
I am also curious about the concern about the battery contactor. In 40+
years of aircraft owning and piloting I have experienced exactly one
battery contactor develop higher than desired resistance, causing
starter performance issues, but it never failed. For it to open implies
that the energy holding the contactor closed is somehow lost. You would
either need the wire providing the ground to close the contactor to
fail, or the coil in the contactor to suddenly develop an open.
I can see one failing to close when master switch is activated, but
having one fail after closing seems to be a very low risk event.
Kelly
On 7/11/2018 7:25 AM, Robert L. Nuckolls, III wrote:
>>
>>
>>
>> On Z14P, if the battery contactor opens then anything on the main
>> battery bus will run until the 17AH main battery dies, right? If you
>> have things like say, an electronic ignition, or electric fuel pump,
>> that are required for flight you'd chug along completely unaware of
>> the disconnect until your engine died, correct?
>
> Yes . . . unless you put low voltage monitoring
> on the battery . . . easy to do. But if engine
> dependency on fuel pressure and ignition is
> addressed by redundant systems, why are they
> all running from one battery?
>
> Bob . . .
>
Message 6
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At 06:42 AM 7/11/2018, you wrote:
>
>hi all,
> in the past a crowbar would stop the current from an overvoltage
> source quick enough to prevent avionics damage.
> is that really needed any more?
OV protection is a legacy component of virtually
all voltage regulators for aviation. You have two
approaches to vetting component reliability: (1) Analyze
or demonstrate component failure rates on the
or of 1 in 10 to the 9th flight hours, i.e. never
fails or (2) ASSUME that it will fail and
mitigate that failure down to a low-risk maintenance
event.
> i have a honda [viking] engine with auto accessories. i don't hear
> of cars blowing out their glass dashboards.
> when i asked b and c about a 'crowbar' they said theirs was only
> recommended for a permanent magnet alternator.
> what are others doing with auto alternators?
Plane Power modifies the automotive alternators
to derive field excitation from a source external
to the alternator. Same with B&C.
PP retains the built in regulator . . . for a time
they added crowbar ov protection externally. Don't
know what they do now. But even if they don't provide
ov protection, it can be easily added to the field
supply feeder. B&C's controllers for their automotive
adaptations have ov protection built in . . . their
PM product installations include/recommend the
crowbar ov protection device which COULD be used
on any other system that is not otherwise fitted
with ov protection.
Emacs!
But if you have a candidate alternator regulator
that you have reason to believe it never fails
then you're certainly free to forego ov protaection.
Bob . . .
Message 7
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| Subject: | Re: Z-* Question |
With the battery contactor working properly, the voltage at the battery
will be "charging voltage" approx. 14 volts. When the battery contactor
fails open, the charge will be removed and the voltage at the battery will
instantly drop to "battery voltage" approx 13 volts. Therefore, if you are
monitoring your voltage at the battery, you will be instantly notified of
the contactor failure
On Tue, Jul 10, 2018 at 6:33 PM BMC_Dave <bmcdave85@gmail.com> wrote:
>
>
> yellowduckduo(at)gmail.co wrote:
> > On 10/07/2018 6:24 PM, BMC_Dave wrote:
> >
> > >
> > >
> > >
> > > nuckolls.bob(at)aeroelect wrote:
> > > > At 11:09 AM 7/10/2018, you wrote:
> > > >
> > > >>
> > > >>
> > > >> Appears to be the same question I raised here:
> http://forum.matronics.com/viewtopic.php?t=16770059 (
> http://forum.matronics.com/viewtopic.php?t=16770059)
> > > >>
> > > >> I get the cautions about making changes, but would this one not
> be prudent?
> > > >>
> > > >> I understand contactor failures are rare, but it is also said
> they wear pretty rough in-service. So why not remove a possible failure
> mode where you don't realize something is wrong until your engine quits?
> > > > Okay, recite the narrative for any particular failure.
> > > > I presume we're talking about Z-14. How would any
> > > > single failure put engine ops at risk?
> > > >
> > > >
> > > > Bob . . .
> > >
> > > I amended that because while I may have been thinking about it in my
> post I didn't actually discuss it. In any case, referring to Z-14 say the
> battery contactor opens in flight. Now the main battery bus is disconnected
> from the alternator, and in this case you have no alternative means to
> connect it to either alternator, so hopefully flight-critical systems
> aren't dependent on it.
> > >
> > > Additionally, you have no warnings that this has occured.
> > > Actually the low battery bus warning should activate as soon as the
> > >
> >
> > battery stopped charging.
> >
> > However I want the alternator to keep charging even if the battery
> > contactor is opened by accident or intent. And I want the alternator
> > charging voltage and the overvoltage protection to apply to the battery
> > buss with minimal resistance in the sense circuit to the VR circuit. I
> > want the engine to keep running if the battery goes open circuit. So I
> > do consider it prudent (but not essential) to connect the alternator as
> > directly as possible to the battery for my electrically dependent engine.
> >
> > Ken
> > Ken
>
>
> I don't see anything on the architecture drawing that would warn you that
> the main battery bus has been disconnected from the alternator(s)
>
>
> nuckolls.bob(at)aeroelect wrote:
> >
> > Z-14's bus loads have quad redundant
> > power sources. Every feeder in the
> > system can get power from multiple
> > sources. Flight critical loads can be
> > shared between two systems such that
> > no single failure puts the flight
> > at risk.
> >
> >
> > Bob . . .
>
>
> On Z14P, if the battery contactor opens then anything on the main battery
> bus will run until the 17AH main battery dies, right? If you have things
> like say, an electronic ignition, or electric fuel pump, that are required
> for flight you'd chug along completely unaware of the disconnect until your
> engine died, correct?
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=481541#481541
>
>
Message 8
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| Subject: | Re: Z-* Question |
nuckolls.bob(at)aeroelect wrote:
>
> >
> >
> >
> > On Z14P, if the battery contactor opens then anything on the main battery
bus will run until the 17AH main battery dies, right? If you have things like
say, an electronic ignition, or electric fuel pump, that are required for flight
you'd chug along completely unaware of the disconnect until your engine died,
correct?
>
> Yes . . . unless you put low voltage monitoring
> on the battery . . . easy to do. But if engine
> dependency on fuel pressure and ignition is
> addressed by redundant systems, why are they
> all running from one battery?
>
>
> Bob . . .
That's the point, in Z14 they don't appear to be, correct?
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=481559#481559
Message 9
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| Subject: | Re: Z-* Question |
It almost feels like I'm being intentionally gaslit, I'll try again. We're addressing
the OPs use of Z14 and his concern about why the alternator isn't on the
battery bus side of the contactor. Additionally, the current architecture doesn't
include any LV warning on the battery bus side.
So as it is drawn currently drawn in Z14, running an electrically dependent engine
is dangerous because you have a single point of failure (the contactor) and
zero indication anything is wrong until your engine dies and you have no means
to turn it back on...
Yes, we discussed adding a LV warning to the battery bus.... in other threads about
other architecture drawings. It's a good idea, you should probably do that,
or similar like putting the LR-3 LV sense on the battery bus instead.
I've heard many times about how contactor failures are rare, once followed immediately
by a description of how hard they wear and steps that can be taken to
mitigate that... Point is this single point of failure is easy to side-step with
out adding anything to the system. The reluctance to do so is confusing and
no one seems to want to explain why.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=481560#481560
Message 10
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On 7/11/2018 6:42 AM, bobnoffs wrote:
>
> hi all,
> in the past a crowbar would stop the current from an overvoltage source quick
enough to prevent avionics damage.
> is that really needed any more?
> i have a honda [viking] engine with auto accessories. i don't hear of cars
blowing out their glass dashboards.
> when i asked b and c about a 'crowbar' they said theirs was only recommended
for a permanent magnet alternator.
> what are others doing with auto alternators?
> thanks
> bob noffs
>
I think their answer was framed in the assumption that you're using only
their products. The B&C regulators for conventional alternators have
overvoltage protection built into them.
I've read 'rumors on the interwebs' that the latest auto tech often
builds voltage regulation into the vehicle's system computer, that
controls virtually everything else in the vehicle, too. Not a big deal
to build in overvoltage protection too, in that environment. It's
unlikely that the Viking is using the stock auto controller (pray that
it doesn't; too many 'protections' in auto controllers that can kill you
in an a/c).
I've run my dirt-simple RV-4 without OV protection for a long time, but
with expensive avionics in the -7 I'm building, I *will* have OV protection.
Charlie
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| Subject: | Making your own fuseable links |
Hi Guys
Where can you get the 'SILICONE COVERED FIBREGLASS SLEEVING' to make your own fuseable
links
Regard: John
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=481564#481564
Message 12
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| Subject: | Re: Z-* Question |
If you "solve" the "problem" by moving the alternator feed wire to the
battery side of the contactor, then you create a separate problem (one many
would consider more serious) in that you will have nullified the ability to
cut off all current by simply moving the master switch.
On Wed, Jul 11, 2018 at 7:40 AM BMC_Dave <bmcdave85@gmail.com> wrote:
>
> It almost feels like I'm being intentionally gaslit, I'll try again. We're
> addressing the OPs use of Z14 and his concern about why the alternator
> isn't on the battery bus side of the contactor. Additionally, the current
> architecture doesn't include any LV warning on the battery bus side.
>
> So as it is drawn currently drawn in Z14, running an electrically
> dependent engine is dangerous because you have a single point of failure
> (the contactor) and zero indication anything is wrong until your engine
> dies and you have no means to turn it back on...
>
> Yes, we discussed adding a LV warning to the battery bus.... in other
> threads about other architecture drawings. It's a good idea, you should
> probably do that, or similar like putting the LR-3 LV sense on the battery
> bus instead.
>
> I've heard many times about how contactor failures are rare, once followed
> immediately by a description of how hard they wear and steps that can be
> taken to mitigate that... Point is this single point of failure is easy to
> side-step with out adding anything to the system. The reluctance to do so
> is confusing and no one seems to want to explain why.
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=481560#481560
>
>
Message 13
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| Subject: | Re: Z-* Question |
> The reluctance to do so is confusing and no one seems to want to explain why.
I explained why. If the alternator "B" lead is connected directly to the battery,
then that "B" lead is always hot no matter if the field switch is on or off.
That always hot wire is more likely to cause an incident than a failed contactor.
The Z figures just show the basic power layout. They are not meant to show every
electrical circuit in an airplane. Notice that there is no radio or EFIS
on the Z figure. It is up to the builder to wire his plane to make it safe.
If you want a low voltage warning, then install it. If there is only one ignition
system, then provide it with two sources of power via diodes or switches.
Just do not make changes that create a new danger.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=481566#481566
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| Subject: | Re: Z-* Question |
kenryan wrote:
> If you "solve" the "problem" by moving the alternator feed wire to the battery
side of the contactor, then you create a separate problem (one many would consider
more serious) in that you will have nullified the ability to cut off all
current by simply moving the master switch.
>
> On Wed, Jul 11, 2018 at 7:40 AM BMC_Dave wrote:
>
>
> >
> > It almost feels like I'm being intentionally gaslit, I'll try again. We're
addressing the OPs use of Z14 and his concern about why the alternator isn't
on the battery bus side of the contactor. Additionally, the current architecture
doesn't include any LV warning on the battery bus side.
> >
> > So as it is drawn currently drawn in Z14, running an electrically dependent
engine is dangerous because you have a single point of failure (the contactor)
and zero indication anything is wrong until your engine dies and you have no
means to turn it back on...
> >
> > Yes, we discussed adding a LV warning to the battery bus.... in other threads
about other architecture drawings. It's a good idea, you should probably do
that, or similar like putting the LR-3 LV sense on the battery bus instead.
> >
> > I've heard many times about how contactor failures are rare, once followed
immediately by a description of how hard they wear and steps that can be taken
to mitigate that... Point is this single point of failure is easy to side-step
with out adding anything to the system. The reluctance to do so is confusing
and no one seems to want to explain why.
> >
> >
> >
> >
> > Read this topic online here:
> >
> > http://forums.matronics.com/viewtopic.php?p=481560#481560 (http://forums.matronics.com/viewtopic.php?p=481560#481560)
> >
> >
> >
> >
> >
> >
> > ==========
> > -
> > Electric-List" rel="noreferrer" target="_blank">http://www.matronics.com/Navigator?AeroElectric-List
> > ==========
> > FORUMS -
> > eferrer" target="_blank">http://forums.matronics.com
> > ==========
> > WIKI -
> > errer" target="_blank">http://wiki.matronics.com
> > ==========
> > b Site -
> > -Matt Dralle, List Admin.
> > rel="noreferrer" target="_blank">http://www.matronics.com/contribution
> > ==========
> >
> >
> >
> >
>
No it doesn't. Moving the alternator feed line to the battery side of the contactor
doesn't change how the Main DC Pwr Master Switch turns off the alternator
(by opening the ALT FLD circuit).
user9253 wrote:
>
> I explained why. If the alternator "B" lead is connected directly to the battery,
then that "B" lead is always hot no matter if the field switch is on or
off.
Electrically, how is having the B lead after the contactor different than having
it before the contactor if the contactor is closed? Should the contactor open,
and your B lead is on the battery side, this would have the same effect as
opening the ALT field circuit, thereby shutting off the alternator. Unless I'm
radically misunderstanding how alternators work...
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=481568#481568
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| Subject: | Re: Z-* Question |
Dave, you are correct that if the alternator is off, that wire will not be
powered by the alternator. It WILL be powered by the battery because you
have connected it directly to the battery right?
On Wed, Jul 11, 2018, 1:59 PM BMC_Dave <bmcdave85@gmail.com> wrote:
>
>
> kenryan wrote:
> > If you "solve" the "problem" by moving the alternator feed wire to the
> battery side of the contactor, then you create a separate problem (one many
> would consider more serious) in that you will have nullified the ability to
> cut off all current by simply moving the master switch.
> >
> > On Wed, Jul 11, 2018 at 7:40 AM BMC_Dave wrote:
> >
> >
> > >
> > > It almost feels like I'm being intentionally gaslit, I'll try again.
> We're addressing the OPs use of Z14 and his concern about why the
> alternator isn't on the battery bus side of the contactor. Additionally,
> the current architecture doesn't include any LV warning on the battery bus
> side.
> > >
> > > So as it is drawn currently drawn in Z14, running an electrically
> dependent engine is dangerous because you have a single point of failure
> (the contactor) and zero indication anything is wrong until your engine
> dies and you have no means to turn it back on...
> > >
> > > Yes, we discussed adding a LV warning to the battery bus.... in other
> threads about other architecture drawings. It's a good idea, you should
> probably do that, or similar like putting the LR-3 LV sense on the battery
> bus instead.
> > >
> > > I've heard many times about how contactor failures are rare, once
> followed immediately by a description of how hard they wear and steps that
> can be taken to mitigate that... Point is this single point of failure is
> easy to side-step with out adding anything to the system. The reluctance to
> do so is confusing and no one seems to want to explain why.
> > >
> > >
> > >
> > >
> > > Read this topic online here:
> > >
> > > http://forums.matronics.com/viewtopic.php?p=481560#481560 (
> http://forums.matronics.com/viewtopic.php?p=481560#481560)
> > >
> > >
> > >
> > >
> > >
> > >
> > > ==========
> > > -
> > > Electric-List" rel="noreferrer" target="_blank">
> http://www.matronics.com/Navigator?AeroElectric-List
> > > ==========
> > > FORUMS -
> > > eferrer" target="_blank">http://forums.matronics.com
> > > ==========
> > > WIKI -
> > > errer" target="_blank">http://wiki.matronics.com
> > > ==========
> > > b Site -
> > > -Matt Dralle, List Admin.
> > > rel="noreferrer" target="_blank">
> http://www.matronics.com/contribution
> > > ==========
> > >
> > >
> > >
> > >
> >
>
>
> No it doesn't. Moving the alternator feed line to the battery side of the
> contactor doesn't change how the Main DC Pwr Master Switch turns off the
> alternator (by opening the ALT FLD circuit).
>
>
> user9253 wrote:
> >
> > I explained why. If the alternator "B" lead is connected directly to
> the battery, then that "B" lead is always hot no matter if the field switch
> is on or off.
>
>
> Electrically, how is having the B lead after the contactor different than
> having it before the contactor if the contactor is closed? Should the
> contactor open, and your B lead is on the battery side, this would have the
> same effect as opening the ALT field circuit, thereby shutting off the
> alternator. Unless I'm radically misunderstanding how alternators work...
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=481568#481568
>
>
Message 16
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| Subject: | Re: Z-* Question |
I do not see the Z-14 as dangerous as drawn for my EFII aircraft. The ECUs can
be split between the busses, the fuel pumps can be split and the injector supply
will be come from a buss powered by both batteries through a diode bridge.
There is no possible way to make any system 100% reliable; if you drill down far
enough, you can't always find a serious failure that will compromise the system.
The point is risk mitigation...
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=481571#481571
Message 17
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| Subject: | Re: Making your own fuseable links |
At 11:32 AM 7/11/2018, you wrote:
><jmtipton@btopenworld.com>
>
>Hi Guys
>
>Where can you get the 'SILICONE COVERED FIBREGLASS SLEEVING' to make
>your own fuseable links
>
>Regard: John
>
https://goo.gl/uuWsgi
Where are you using a fusible link?
Bob . . .
Message 18
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| Subject: | Re: Z-* Question |
At 10:34 AM 7/11/2018, you wrote:
>
>It almost feels like I'm being intentionally gaslit, I'll try again.
>We're addressing the OPs use of Z14 and his concern about why the
>alternator isn't on the battery bus side of the contactor.
So the b-lead is 'cold' when the master switch is OFF
> Additionally, the current architecture doesn't include any LV
> warning on the battery bus side.
Because in-flight contactor failure rates are very
low. But if one wishes to 'cover' that possibility,
lv warning on a battery-bus fed appliance would
provide the hedge.
Bob . . .
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| Subject: | Re: Z-* Question |
cluros(at)gmail.com wrote:
> Dave, you are correct that if the alternator is off, that wire will not be powered
by the alternator. It WILL be powered by the battery because you have connected
it directly to the battery right?
>
>
Ahhh, I see it now thanks. Yeah that's true, though I'm not positive on the placement
of these things in relation to each other. If going to the starter contactor
is a whole lot different than going to the bat side of the battery contactor.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=481573#481573
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| Subject: | Re: Z-* Question |
> >
> > Yes . . . unless you put low voltage monitoring
> > on the battery . . . easy to do. But if engine
> > dependency on fuel pressure and ignition is
> > addressed by redundant systems, why are they
> > all running from one battery?
> >
> >
> > Bob . . .
>
>
>That's the point, in Z14 they don't appear to be, correct?
Correct. I have shown primary systems on main battery,
secondary on the aux battery . . . hence even loss
of one battery contactor does not present an
intractable hazzard to comfortable termination
of flight. I have been assuming (possibly incorrectly)
that there was some feature of this discussion that
absolutely depended on energy from a single
battery bus for continued flight.
Bob . . .
Message 21
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| Subject: | Re: Z-* Question |
Rocketman1988 wrote:
> I do not see the Z-14 as dangerous as drawn for my EFII aircraft. The ECUs can
be split between the busses, the fuel pumps can be split and the injector supply
will be come from a buss powered by both batteries through a diode bridge.
>
> There is no possible way to make any system 100% reliable; if you drill down
far enough, you can't always find a serious failure that will compromise the system.
The point is risk mitigation...
Fair enough, I just see the architecture as-drawn to have a pretty serious single
point of failure for electronically dependent engines. As it can occur with
no notice to the pilot that something has happened, and no way to provide power
to the bits that need it once your engine shuts off. The reluctance to acknowledge
this is perplexing.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=481576#481576
Message 22
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| Subject: | Re: Z-* Question |
The starter contactor is on the other side of the battery contactor. With
the battery contactor off, no battery power to the starter contactor, no
battery power to the b lead.
On Wed, Jul 11, 2018, 2:46 PM BMC_Dave <bmcdave85@gmail.com> wrote:
>
>
> cluros(at)gmail.com wrote:
> > Dave, you are correct that if the alternator is off, that wire will not
> be powered by the alternator. It WILL be powered by the battery because you
> have connected it directly to the battery right?
> >
> >
>
>
> Ahhh, I see it now thanks. Yeah that's true, though I'm not positive on
> the placement of these things in relation to each other. If going to the
> starter contactor is a whole lot different than going to the bat side of
> the battery contactor.
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=481573#481573
>
>
Message 23
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| Subject: | Re: Z-* Question |
If one incorporates the Z-24 OVP protection for internal VR
alternators, that OVP contactor or relay disconnects the battery from
the B lead if the alternator is turned off.
Ken
On 11/07/2018 2:15 PM, Sebastien wrote:
> Dave, you are correct that if the alternator is off, that wire will
> not be powered by the alternator. It WILL be powered by the battery
> because you have connected it directly to the battery right?
>
> On Wed, Jul 11, 2018, 1:59 PM BMC_Dave <bmcdave85@gmail.com
> <mailto:bmcdave85@gmail.com>> wrote:
>
> <bmcdave85@gmail.com <mailto:bmcdave85@gmail.com>>
>
>
> kenryan wrote:
> > If you "solve" the "problem" by moving the alternator feed wire
> to the battery side of the contactor, then you create a separate
> problem (one many would consider more serious) in that you will
> have nullified the ability to cut off all current by simply moving
> the master switch.
> >
> > On Wed, Jul 11, 2018 at 7:40 AM BMC_Dave wrote:
> >
> >
> > >
> > > It almost feels like I'm being intentionally gaslit, I'll try
> again. We're addressing the OPs use of Z14 and his concern about
> why the alternator isn't on the battery bus side of the contactor.
> Additionally, the current architecture doesn't include any LV
> warning on the battery bus side.
> > >
> > > So as it is drawn currently drawn in Z14, running an
> electrically dependent engine is dangerous because you have a
> single point of failure (the contactor) and zero indication
> anything is wrong until your engine dies and you have no means to
> turn it back on...
> > >
> > > Yes, we discussed adding a LV warning to the battery bus....
> in other threads about other architecture drawings. It's a good
> idea, you should probably do that, or similar like putting the
> LR-3 LV sense on the battery bus instead.
> > >
> > > I've heard many times about how contactor failures are rare,
> once followed immediately by a description of how hard they wear
> and steps that can be taken to mitigate that... Point is this
> single point of failure is easy to side-step with out adding
> anything to the system. The reluctance to do so is confusing and
> no one seems to want to explain why.
> > >
> > >
> > >
> > >
> > > Read this topic online here:
> > >
> > > http://forums.matronics.com/viewtopic.php?p=481560#481560
> (http://forums.matronics.com/viewtopic.php?p=481560#481560)
> > >
> > >
> > >
> > >
> > >
> > >
> > > ==========
> > > -
> > > Electric-List" rel="noreferrer"
> target="_blank">http://www.matronics.com/Navigator?AeroElectric-List
> > > ==========
> > > FORUMS -
> > > eferrer" target="_blank">http://forums.matronics.com
> > > ==========
> > > WIKI -
> > > errer" target="_blank">http://wiki.matronics.com
> > > ==========
> > > b Site -
> > > -Matt Dralle, List Admin.
> > > rel="noreferrer"
> target="_blank">http://www.matronics.com/contribution
> > > ==========
> > >
> > >
> > >
> > >
> >
>
>
> No it doesn't. Moving the alternator feed line to the battery side
> of the contactor doesn't change how the Main DC Pwr Master Switch
> turns off the alternator (by opening the ALT FLD circuit).
>
>
> user9253 wrote:
> >
> > I explained why. If the alternator "B" lead is connected
> directly to the battery, then that "B" lead is always hot no
> matter if the field switch is on or off.
>
>
> Electrically, how is having the B lead after the contactor
> different than having it before the contactor if the contactor is
> closed? Should the contactor open, and your B lead is on the
> battery side, this would have the same effect as opening the ALT
> field circuit, thereby shutting off the alternator. Unless I'm
> radically misunderstanding how alternators work...
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=481568#481568
>
>
> ==========
> -
> Electric-List" rel="noreferrer noreferrer"
> target="_blank">http://www.matronics.com/Navigator?AeroElectric-List
> ==========
> FORUMS -
> eferrer noreferrer" target="_blank">http://forums.matronics.com
> ==========
> WIKI -
> errer noreferrer" target="_blank">http://wiki.matronics.com
> ==========
> b Site -
> -Matt Dralle, List Admin.
> rel="noreferrer noreferrer"
> target="_blank">http://www.matronics.com/contribution
> ==========
>
>
Message 24
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| Subject: | Re: Z-* Question |
So the reasoning is that having an always-hot B lead is more dangerous than the
single point failure of the battery contactor? If I'm finally getting that point?
Is sparking of a severed B lead the only concern, or is there something else about
having the alternator always hot that is no bueno? How long is that 10 AWG
run from the AUX ALT?
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=481579#481579
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| Subject: | Re: Z-* Question |
At 01:47 PM 7/11/2018, you wrote:
>
>
>Rocketman1988 wrote:
> > I do not see the Z-14 as dangerous as drawn for my EFII
> aircraft. The ECUs can be split between the busses, the fuel pumps
> can be split and the injector supply will be come from a buss
> powered by both batteries through a diode bridge.
> >
> > There is no possible way to make any system 100% reliable; if you
> drill down far enough, you can't always find a serious failure that
> will compromise the system. The point is risk mitigation...
>
>
>Fair enough, I just see the architecture as-drawn to have a pretty
>serious single point of failure for electronically dependent
>engines. As it can occur with no notice to the pilot that something
>has happened, and no way to provide power to the bits that need it
>once your engine shuts off. The reluctance to acknowledge this is perplexing.
I don't think anyone is failing to acknowledge
anything. You have hypothesized a suite
of hardware that is not illustrated in Z-14.
As published, Z-14 purports to show that
redundant systems can improve on system
reliability by feeding them from separate
power systems . . . where it has been
judged that no single failure puts the
aircraft at risk.
If some primary component is not backed
up with a secondary -and- assuming that it
has only one feed point for power,
Z-14 offers no advice and the system
may benefit from some adjustments.
If an alternator feed is moved to the
battery (like 100% of cars) then the
regulator supply and voltage sense
must also be moved to the battery side
of the contactor as well. From a
performance perspective, there's nothing
wrong with it . . . and it would mitigate
the failed contactor scenario.
The only down side is that the b-lead
is hot all the time. This has post
crash safety implications and maintenance
implications (be sure to unhook battery(-)
before turning wrenches under the cowl
just like you do on your car.
Bob . . .
Message 26
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| Subject: | Re: Z-* Question |
If you look in the very bottom left corner of Z-14 at the aux battery bus, there
are secondary ignition and secondary fuel pump fuses. So there is no single
point of failure. If the main battery completely shorts out and dies, the engine
keeps running because it will get electricity from the aux battery and aux
alternator.
It might be confusing because the aux bus is drawn with part of it horizontal
and part of it vertical.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=481582#481582
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| Subject: | Re: Z-* Question |
BMC_Dave wrote:
>
> Rocketman1988 wrote:
> > I do not see the Z-14 as dangerous as drawn for my EFII aircraft. The ECUs
can be split between the busses, the fuel pumps can be split and the injector
supply will be come from a buss powered by both batteries through a diode bridge.
> >
> > There is no possible way to make any system 100% reliable; if you drill down
far enough, you can't always find a serious failure that will compromise the
system. The point is risk mitigation...
>
>
> Fair enough, I just see the architecture as-drawn to have a pretty serious single
point of failure for electronically dependent engines. As it can occur with
no notice to the pilot that something has happened, and no way to provide power
to the bits that need it once your engine shuts off. The reluctance to acknowledge
this is perplexing.
Ok, where specifically is the issue? The essentials will be powered by a buss
supplied by BOTH batteries through a diode bridge. So:
one contractor fails > engine keeps running
one alternator fails > engine keeps running
one battery fails > engine keeps running
If the essentials include a fuel pump and ECU then:
two alternators and 1 battery fail > engine keeps running.
I have intentionally left the EFIS and radios from this discussion, focusing on
only the engine.
Short of a combined multiple failure > engine keeps running.
Please explain your how the Z-14 as drawn has a single point of failure...
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=481583#481583
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| Subject: | Re: Z-* Question |
Rocketman1988 wrote:
>
> BMC_Dave wrote:
> >
> > Rocketman1988 wrote:
> > > I do not see the Z-14 as dangerous as drawn for my EFII aircraft. The ECUs
can be split between the busses, the fuel pumps can be split and the injector
supply will be come from a buss powered by both batteries through a diode bridge.
> > >
> > > There is no possible way to make any system 100% reliable; if you drill down
far enough, you can't always find a serious failure that will compromise the
system. The point is risk mitigation...
> >
> >
> > Fair enough, I just see the architecture as-drawn to have a pretty serious
single point of failure for electronically dependent engines. As it can occur
with no notice to the pilot that something has happened, and no way to provide
power to the bits that need it once your engine shuts off. The reluctance to
acknowledge this is perplexing.
>
>
> Ok, where specifically is the issue? The essentials will be powered by a buss
supplied by BOTH batteries through a diode bridge. So:
>
> one contractor fails > engine keeps running
> one alternator fails > engine keeps running
> one battery fails > engine keeps running
>
> If the essentials include a fuel pump and ECU then:
>
> two alternators and 1 battery fail > engine keeps running.
>
> I have intentionally left the EFIS and radios from this discussion, focusing
on only the engine.
>
> Short of a combined multiple failure > engine keeps running.
>
> Please explain your how the Z-14 as drawn has a single point of failure...
Battery contactor fails, engine keeps running... until?
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=481585#481585
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| Subject: | Re: Z-* Question |
user9253 wrote:
> If you look in the very bottom left corner of Z-14 at the aux battery bus, there
are secondary ignition and secondary fuel pump fuses. So there is no single
point of failure. If the main battery completely shorts out and dies, the
engine keeps running because it will get electricity from the aux battery and
aux alternator.
> It might be confusing because the aux bus is drawn with part of it horizontal
and part of it vertical.
Aren't those two separate buses?
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=481586#481586
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| Subject: | Re: Z-* Question |
On 7/11/2018 3:04 PM, BMC_Dave wrote:
>
>
> user9253 wrote:
>> If you look in the very bottom left corner of Z-14 at the aux battery bus, there
are secondary ignition and secondary fuel pump fuses. So there is no single
point of failure. If the main battery completely shorts out and dies, the
engine keeps running because it will get electricity from the aux battery and
aux alternator.
>> It might be confusing because the aux bus is drawn with part of it horizontal
and part of it vertical.
>
> Aren't those two separate buses?
>
Yes; driving two separate engine controllers (ignitions). If the main
contactor fails, and you fly the plane to main battery depletion, the
2nd engine controller keeps the engine running. You'll surely know you
have a problem the next time you try to start the plane, even if you've
managed to miss all the signs up to that point.
As everyone keeps saying, the Z figures are templates; *not* finished
schematics that can't be adjusted to fit individual needs. If you're
running a single ignition controller, fed by the battery bus, and if,
overall, you like Z-14 for your purposes, then add low voltage
monitoring to the battery bus. Wouldn't that solve your issue of
undetected contactor failure? If you like moving the B lead to the
battery bus, then add a contactor to the B lead so it can be interrupted
when the a/c is powered down (crash & maintenance protection). Or, if
you're comfortable with the B lead being always hot, and you're aware of
the implications, then hook it up that way, and move your high/low
voltage protection/monitoring to the battery bus.
Charlie
---
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Message 31
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| Subject: | Re: Z-* Question |
At 03:04 PM 7/11/2018, you wrote:
>
>
>user9253 wrote:
> > If you look in the very bottom left corner of Z-14 at the aux
> battery bus, there are secondary ignition and secondary fuel pump
> fuses. So there is no single point of failure. If the main
> battery completely shorts out and dies, the engine keeps running
> because it will get electricity from the aux battery and aux alternator.
> > It might be confusing because the aux bus is drawn with part of
> it horizontal and part of it vertical.
>
Figure 17-5 in the 'Connection is accompanied by
a narrative describing the philosophy behind
Z-14.
The idea was to craft two, independent systems
that could be used in tandem for some flight
conditions:
Emacs!
A cross-feed contactor could be closed during engine
cranking to offer better starter performance. All
normal ops are conducted with the cross-feed open.
If an alternator is lost, the cross-feed contactor
can be closed to share power offered by the remaining
alternator. A feeder off any of the four busses has
access to four power sources. This means that no
endurance bus is needed.
When electrically dependent power plants are
fitted with redundant sub-systems, then those
pairs are distributed between the two battery
busses.
With the exception of battery contactor loss, it is
exceedingly unlikely that any battery bus becomes
un-powered . . . and only after that battery
is depleted.
The only time that condition elevates risk is when a
non-redundant power plant subsystem is powered from
that bus.
This discussion underscores the value of doing
the load analysis for various flight conditions
combined with the FMEA to ensure power
distribution to accessories needed for comfortable
termination of flight.
Bob . . .
Message 32
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Different alternators have different failure mode. I recently saw a friends
Cessna 172 after it suffered some sort of over voltage condition. If. I had
not seen it, I would not have believed the damage. Every electrical component
was fried. The insulation on every wire was burned. I did not know an
alternator was capable of that sort of damage. I do know a crowbar would have
Prevented it though. Like I said, if I had not personally seen the damage
I would not have believed how bad it was. Every wire and electrical component
in the airplane had to be replaced. It is possible that not all alternators
are capable of that sort of failure mode. But it sure opened my eyes and I
would not want to have been on board when it occurred. Jim Kale, Enterprise,
AL
Sent from my iPhone
> On Jul 11, 2018, at 10:45 AM, Charlie England <ceengland7@gmail.com> wrote:
>
>
>> On 7/11/2018 6:42 AM, bobnoffs wrote:
>>
>> hi all,
>> in the past a crowbar would stop the current from an overvoltage source quick
enough to prevent avionics damage.
>> is that really needed any more?
>> i have a honda [viking] engine with auto accessories. i don't hear of cars
blowing out their glass dashboards.
>> when i asked b and c about a 'crowbar' they said theirs was only recommended
for a permanent magnet alternator.
>> what are others doing with auto alternators?
>> thanks
>> bob noffs
>>
> I think their answer was framed in the assumption that you're using only their
products. The B&C regulators for conventional alternators have overvoltage protection
built into them.
>
> I've read 'rumors on the interwebs' that the latest auto tech often builds voltage
regulation into the vehicle's system computer, that controls virtually everything
else in the vehicle, too. Not a big deal to build in overvoltage protection
too, in that environment. It's unlikely that the Viking is using the stock
auto controller (pray that it doesn't; too many 'protections' in auto controllers
that can kill you in an a/c).
>
> I've run my dirt-simple RV-4 without OV protection for a long time, but with
expensive avionics in the -7 I'm building, I *will* have OV protection.
>
> Charlie
>
> ---
> This email has been checked for viruses by Avast antivirus software.
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>
>
>
>
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