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You think alternators are safe?

 
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frank.hinde(at)hp.com
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PostPosted: Thu Feb 16, 2006 1:57 pm    Post subject: You think alternators are safe? Reply with quote

Afternoon all,

One of my part time jobs is to be on call as an Incident commander for a
large blue chip wafer fab plant.

Last night we had a Ford Mustang pull into one of our employee parking
lots and the "charge lamp" came on as the employee was looking for his
spot.

Half an hour later (12:30 am thankyou!) I was awoken by the pager going
off saying the car was on fire. And had had involved 4 other vehicles.

By the time the Fire Deprtment got there the thing was fully engulfed
with 20 foot flames...Fortunatly the gas tank was not involved.

This morning...sure enough, signs that the fire started at the
alternator but the battery was completely melted in what looks like
feeding an internal short on the alternator.

Of course you know I was thinking, "I sure glad to have a way to
disconnect the alt"!!!

Frank
Zodiac flying 400 hours
RV7a finishing up prior to paint


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nuckollsr(at)cox.net
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PostPosted: Thu Feb 16, 2006 4:27 pm    Post subject: You think alternators are safe? Reply with quote

At 01:55 PM 2/16/2006 -0800, you wrote:

Quote:

<frank.hinde(at)hp.com>

Afternoon all,

One of my part time jobs is to be on call as an Incident commander for a
large blue chip wafer fab plant.

Last night we had a Ford Mustang pull into one of our employee parking
lots and the "charge lamp" came on as the employee was looking for his
spot.

Half an hour later (12:30 am thankyou!) I was awoken by the pager going
off saying the car was on fire. And had had involved 4 other vehicles.

By the time the Fire Deprtment got there the thing was fully engulfed
with 20 foot flames...Fortunatly the gas tank was not involved.

This morning...sure enough, signs that the fire started at the
alternator but the battery was completely melted in what looks like
feeding an internal short on the alternator.

Of course you know I was thinking, "I sure glad to have a way to
disconnect the alt"!!!

This is the one fallacy in the automotive fusible-link philosophy.
Fusible links do fine for hard faults (over in tens of milliseconds
and relatively low energy). However, like ANL current limiters, they're
even more insensitive to soft faults that can operate for protracted
periods of time and dump megajoules of energy into the surrounding
combustibles.

This is a hypothesis of course but the alternators are generally
hard-wired to the battery with only a fusible link for fault protection.
I've had several wrestling matches with both engineers and regulatory
bureaucrats about the relative safety of conventional fuses, breakers
and limiters for certain applications. AC43-13 states:

11-48. DETERMINATION OF CIRCUIT
BREAKER RATINGS. Circuit protection
devices must be sized to supply open circuit
capability. A circuit breaker must be rated so
that it will open before the current rating of the
wire attached to it is exceeded, or before the
cumulative rating of all loads connected to it
are exceeded, whichever is lowest. A circuit
breaker must always open before any component
downstream can overheat and generate
smoke or fire. Wires must be sized to carry
continuous current in excess of the circuit
protective device rating, including its time current
characteristics, and to avoid excessive
voltage drop. Refer to section 5 for wire rating
methods.

If this is interpreted to be a requirement, then it cannot
be complied with using contemporary I(squared)*R overcurrent
detecting devices; I.e., thermal breakers, fat fuses or
ANL limiters and particularly fusible links.

Bob . . .


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frank.hinde(at)hp.com
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PostPosted: Fri Feb 17, 2006 6:53 am    Post subject: You think alternators are safe? Reply with quote

I think this means...Fusable links can start a fire before the fuse
blows?....Smile

Therein lies the problem with 12V power presumably.

Frank

If this is interpreted to be a requirement, then it cannot
be complied with using contemporary I(squared)*R overcurrent
detecting devices; I.e., thermal breakers, fat fuses or
ANL limiters and particularly fusible links.

Bob . . .


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klehman(at)albedo.net
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PostPosted: Fri Feb 17, 2006 7:56 am    Post subject: You think alternators are safe? Reply with quote

If a device can get hot enough to ignite itself or its surroundings
without tripping the fuse or whatever overcurrent protection is in use,
then a fire will result. AC or DC makes no difference. The type of
remotely located overcurrent protection fuse/fusiblelink/CB makes no
difference. (Well OK it could make a slight difference in cases where a
fast fuse blows before slower protection but I'm assuming the current is
below what will trigger any overcurrent protection) We size the fuse to
protect the wire but generally have little control over what is in the
device that the wire is connected to. This scenario is more common when
ciruitry is connected in parallel with a single overcurrent protection
device and one branch shorts but not hard enough to blow the fuse. And
of course in some cases all it takes is a wee spark to start a fire.

The next level of remote protection is probably a ground fault device.
Even they only protect against one type of circuit failure but they can
be helpful with some devices that are prone to develop hazardous leakage
current paths to ground.

There is an argument that a shorted stator winding will blow an open
circuit in its diodes and not be a hazard but unfortunately diodes can
also fail shorted. Kind of reminds me of the argument that the field
transistor can't fail shorted but in any case it also seems prudent to
me to keep my OV contactor to enable disconnecting the alternator. If my
suspicions that scenarios like this do actually occur with stators is
correct, then I don't believe an external VR alternator would offer any
additional protection compared to an internal VR unit with this type of
fault.

Ken
Hinde, Frank George (Corvallis) wrote:

Quote:


I think this means...Fusable links can start a fire before the fuse
blows?....Smile

Therein lies the problem with 12V power presumably.

Frank

If this is interpreted to be a requirement, then it cannot
be complied with using contemporary I(squared)*R overcurrent
detecting devices; I.e., thermal breakers, fat fuses or
ANL limiters and particularly fusible links.

Bob . . .





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gmcjetpilot(at)yahoo.com
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PostPosted: Fri Feb 17, 2006 8:59 am    Post subject: You think alternators are safe? Reply with quote

Quote:
From: <frank.hinde(at)hp.com>
"Hinde, Frank George (Corvallis)"
Subject: You think alternators are safe?

No! Take them out.

You are right you should not have an alternator or battery they
are dangerous. Get a glider or an ultralight with a pull start.
I think its mostly Fords Frank.

Quote:
Afternoon all, One of my part time jobs is to be on call as an
Incident commander for a large blue chip wafer fab plant.

You get to sleep and get paid. America is wonderful.

Quote:
Last night we had a Ford Mustang pull into one of our
employee parking lots and the "charge lamp" came on as the
employee was looking for his spot.

Looked it up did not make the web News. I guess Fords
catching on fire is not news; it happens so much.

Quote:
Half an hour later (12:30 am thankyou!) I was awoken by
the pager going off saying the car was on fire. And had
involved 4 other vehicles. By the time the Fire Department
got there the thing was fully engulfed with 20 foot
flames...Fortunately the gas tank was not involved.

Fords catching on fire, consumer complaints, safety alerts,
service bulletins and recalls and lawsuits are common.

http://www.fordfires.com/
http://www.interfire.org/res_file/fseab_tv.asp
http://www.vehicle-injuries.com/ford-fire.htm
http://www.wesh.com/news/4606995/detail.html


>This morning...sure enough, signs that the fire started at the
Quote:
alternator but the battery was completely melted in what
looks like feeding an internal short on the alternator.

Here is a partial list of Ford electrical fire recalls:

Make: FORD
Model: WINDSTAR
Year: 1995
Recall Number: 94V223000
Summary: THE ALTERNATOR OUTPUT WIRE WAS
NOT CONNECTED TIGHTLY TO THE POWER
DISTRIBUTION BOX.
Consequence:
THIS CAN RESULT IN OVERHEATING OF THE
CONNECTION AND A POSSIBLE VEHICLE **FIRE**.
Remedy:
DEALERS WILL INSPECT AND TIGHTEN THE
CONNECTION. VEHICLES WITH VISIBLE DAMAGE TO
THE PLASTIC POWER DISTRIBUTION BOX HOUSING
WILL HAVE THE UNDERHOOD HARNESS, INCLUDING
THE POWER DISTRIBUTION BOX, REPLACED.


Make/Model: 1999 Mercury Cougar
Recall ID from NHTSA: 01V031000;
Recall Date: 02/06/2001
Component: ELECTRICAL BATTERY:CABLES
Potential Units Affected: 120000
Summary: VEHICLE DESCRIPTION: PASSENGER
VEHICLES EQUIPPED WITH 2.5L V6 ENGINES. THE
BATTERY CABLE WAS MISROUTED AND ITS
ATTACHMENT TO THE ALTERNATOR CABLE WAS
UNDER-TORQUED. IF MISROUTED, THE CABLE COULD
CONTACT THE POWER STEERING LINE AND THE
INSULATION COULD WEAR, RESULTING IN AN
ELECTRICAL SHORT.
Defect Consequence: THE SHORT COULD POTENTIALLY
RESULT IN A **FIRE**, STALLING, OR A NO-START
CONDITION.

Electrical/ **Fires**:
Tow package relay short, 60,000 1986-88 Aerostar (88V-091);
Power seat short, 90,000 1986 Aerostar (88V-145);
Alternator output wire short 112,000 1995 Windstar (94V-223);
Ignition switch short, 200,000+ 1988-91 Aerostar - (96V-071);
Fuel pump wiring harness short 1994-95 Aerostar (99V-028);
Accessory power feed circuit short 757,000 1992-97 Aerostar
(99V-029).



Quote:
Of course you know I was thinking, "I sure glad to have a way
to disconnect the alt"!!!

Me to. That is what the BIG pull-able CB on my panel is for.

Have a way to Pull a CB to disconnect the alternator.
Idiot light comes on Pull CB and land (or park)
Lesson learned have tight connections
Don't use Ford parts

Quote:
Frank, Zodiac flying 400 hours,
RV7a finishing up prior to paint

Cheers George


---------------------------------
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n801bh(at)NetZero.com
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PostPosted: Fri Feb 17, 2006 1:30 pm    Post subject: You think alternators are safe? Reply with quote

Lesson learned have tight connections
Don't use Ford parts


/////////////////////////////////
Dem dare fighin words....................................
Jus kiddin ,,,,altho the V-8 Ford in my plane just keeps tickin along. It doesn't have any ford electrical parts in it tho..... <G>
do not archive
Ben Haas
N801BH
www.haaspowerair.com

Lesson learned have tight connections
Don't use Ford parts


/////////////////////////////////


Dem dare fighin words....................................


Jus kiddin ,,,,altho the V-8 Fordin my plane just keeps tickin along. It doesn't have any ford electrical parts in it tho..... G


do not archive
BenHaas
N801BH
www.haaspowerair.com


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deej(at)deej.net
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PostPosted: Fri Feb 17, 2006 1:45 pm    Post subject: You think alternators are safe? Reply with quote

n801bh(at)netzero.com wrote:

Quote:
Jus kiddin ,,,,altho the V-8 Ford in my plane just keeps tickin along. It doesn't have any ford electrical parts in it tho..... <G>
do not archive



Ticking? I don't think it is supposed to do that... *wink*

do not archive

-Dj

--
Dj Merrill
Glastar Sportsman 2+2 Builder #7118

"Many things that are unexplainable happen during the construction of an
airplane." --Dave Prizio, 30 Aug 2005

"TSA: Totally Screwing Aviation"


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capsteve



Joined: 09 Jan 2006
Posts: 111
Location: NIAGARA FALLS NY

PostPosted: Fri Feb 17, 2006 8:02 pm    Post subject: You think alternators are safe? Reply with quote

Let it be known that it's not standard practice for any automotive
manufacturer to protect the alt charging lead or the starter supply wire.
Well, I'm sure there are a "few" exceptions, but I've been contracted to
restore more than a few electrical fireballs. Most recently a 2002 Lexus
gs430 almost met its end when the 4ga starter supply wire met the exhaust
manifold and began to discharge the battery at an accelerated pace. The
braided ground to the engine failed, then the alternate ground paths had to
carry the heavy load. Primarily sensor grounds to the ecm, which then begin
to overheat within the larger harnesses and begin to fuse to other
wires/circuits which propagate the process until either the battery melts
internally and goes critical or discharges.
I've measured inrush currents to some gm starters at over 230 amp which
would make fusing difficult, perhaps they figure why bother??
Alternators typically rated at 100 or 120 amp would be relatively easy to
fuse, but I don't know why they aren't. perhaps the risks that the
alternator melts down internally or the 8ga feed to the batt becomes
compromised is less than the risk that the fuse inline may false and require
a service dept visit.

Just .02

Steven dinieri
Rv221rv
Quote:
"Hinde, Frank George (Corvallis)"
Subject: You think alternators are safe?

No! Take them out.

You are right you should not have an alternator or battery they
are dangerous. Get a glider or an ultralight with a pull start.
I think its mostly Fords Frank.

Quote:
Afternoon all, One of my part time jobs is to be on call as an
Incident commander for a large blue chip wafer fab plant.

You get to sleep and get paid. America is wonderful.

Quote:
Last night we had a Ford Mustang pull into one of our
employee parking lots and the "charge lamp" came on as the
employee was looking for his spot.

Looked it up did not make the web News. I guess Fords
catching on fire is not news; it happens so much.

Quote:
Half an hour later (12:30 am thankyou!) I was awoken by
the pager going off saying the car was on fire. And had
involved 4 other vehicles. By the time the Fire Department
got there the thing was fully engulfed with 20 foot
flames...Fortunately the gas tank was not involved.

Fords catching on fire, consumer complaints, safety alerts,
service bulletins and recalls and lawsuits are common.

http://www.fordfires.com/
http://www.interfire.org/res_file/fseab_tv.asp
http://www.vehicle-injuries.com/ford-fire.htm
http://www.wesh.com/news/4606995/detail.html


>This morning...sure enough, signs that the fire started at the
Quote:
alternator but the battery was completely melted in what
looks like feeding an internal short on the alternator.

Here is a partial list of Ford electrical fire recalls:

Make: FORD
Model: WINDSTAR
Year: 1995
Recall Number: 94V223000
Summary: THE ALTERNATOR OUTPUT WIRE WAS
NOT CONNECTED TIGHTLY TO THE POWER
DISTRIBUTION BOX.
Consequence:
THIS CAN RESULT IN OVERHEATING OF THE
CONNECTION AND A POSSIBLE VEHICLE **FIRE**.
Remedy:
DEALERS WILL INSPECT AND TIGHTEN THE
CONNECTION. VEHICLES WITH VISIBLE DAMAGE TO
THE PLASTIC POWER DISTRIBUTION BOX HOUSING
WILL HAVE THE UNDERHOOD HARNESS, INCLUDING
THE POWER DISTRIBUTION BOX, REPLACED.


Make/Model: 1999 Mercury Cougar
Recall ID from NHTSA: 01V031000;
Recall Date: 02/06/2001
Component: ELECTRICAL BATTERY:CABLES
Potential Units Affected: 120000
Summary: VEHICLE DESCRIPTION: PASSENGER
VEHICLES EQUIPPED WITH 2.5L V6 ENGINES. THE
BATTERY CABLE WAS MISROUTED AND ITS
ATTACHMENT TO THE ALTERNATOR CABLE WAS
UNDER-TORQUED. IF MISROUTED, THE CABLE COULD
CONTACT THE POWER STEERING LINE AND THE
INSULATION COULD WEAR, RESULTING IN AN
ELECTRICAL SHORT.
Defect Consequence: THE SHORT COULD POTENTIALLY
RESULT IN A **FIRE**, STALLING, OR A NO-START
CONDITION.

Electrical/ **Fires**:
Tow package relay short, 60,000 1986-88 Aerostar (88V-091);
Power seat short, 90,000 1986 Aerostar (88V-145);
Alternator output wire short 112,000 1995 Windstar (94V-223);
Ignition switch short, 200,000+ 1988-91 Aerostar - (96V-071);
Fuel pump wiring harness short 1994-95 Aerostar (99V-028);
Accessory power feed circuit short 757,000 1992-97 Aerostar
(99V-029).



Quote:
Of course you know I was thinking, "I sure glad to have a way
to disconnect the alt"!!!

Me to. That is what the BIG pull-able CB on my panel is for.

Have a way to Pull a CB to disconnect the alternator.
Idiot light comes on Pull CB and land (or park)
Lesson learned have tight connections
Don't use Ford parts

Quote:
Frank, Zodiac flying 400 hours,
RV7a finishing up prior to paint

Cheers George


---------------------------------
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nuckollsr(at)cox.net
Guest





PostPosted: Sat Feb 18, 2006 9:41 am    Post subject: You think alternators are safe? Reply with quote

At 06:50 AM 2/17/2006 -0800, you wrote:

Quote:

<frank.hinde(at)hp.com>

I think this means...Fusable links can start a fire before the fuse
blows?....Smile

Therein lies the problem with 12V power presumably.

Frank

If this is interpreted to be a requirement, then it cannot
be complied with using contemporary I(squared)*R overcurrent
detecting devices; I.e., thermal breakers, fat fuses or
ANL limiters and particularly fusible links.

Bob . . .

This isn't a system voltage or DC versus AC issue. This is
a hard fact of physics in all power systems. The paragraph
I cited from AC43-13 completely ignores the "soft fault"
phenomenon that may occur at any voltage level, any current
level and in AC or DC systems.

Example: A C-90 on short final to Clovis NM about 1990 was
suddenly stricken with complete disconnect of control in pitch.
Elevator forces in wheel went to zero. The pilots did a go around
and managed to land safely with power and pitch trim.

A teardown revealed a mis-positioned wire bundle under the
floorboards where a 40A protected wire for co-pilot's windshield
heat had had been rubbing against the elevator cable for some
period of time.

No smoke, no fire, no flickers in the electrical system, no
trips of the 40A breaker. Over the pre-failure interval,
megajoules of energy were released in the erosion of steel
wires (the copper wire was in pretty good shape . . . this
demonstrates why layers of copper are included in the design
of safes . . . nearly impossible to penetrate with a cutting
torch).

In other instances, it's easy to imagine a 10-cent resistor
burning up in a radio and making lots of nasty smells in the
cockpit while failing to open a 5A fuse that protects the
feed wire to the failed device.

Bottom line is that ALL thermally actuated protective devices
(fuses, heater actuated breakers, current limiters, fusible
links) and even magnetic breakers are incapable of reacting to
the low-rate, long-duration soft faults that are exemplified
by the two scenarios I offered above. This illustrates the silliness
of any designer (or bureaucrat) who believes that AC43-13/11-48
can be complied with.

Since the Swiss Air 111 accident, there has been
a lot work to develop miniature breakers fitted with little
digital signal processing receivers designed to listen for
and react to unique signal characteristics of a low current
electrical arc. These probably won't keep 10-cent resistors
from smoking but they WOULD have prevented damage to the
C-90's elevator cable and probably would have prevented the
Swiss Air 111 incident.

It's the system designer's goal to UNDERSTAND the technology
behind products he/she includes in the system and in particular,
limits that are not articulated in spec sheets.

Bob . . .


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n801bh(at)netzero.com
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PostPosted: Sat Feb 18, 2006 10:06 am    Post subject: You think alternators are safe? Reply with quote

Very well spoken,, as usual.

do not archive

Ben Haas
N801BH
www.haaspowerair.com


Very well spoken,, as usual.

do not archive

BenHaas
N801BH
www.haaspowerair.com


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endspeed(at)yahoo.com
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PostPosted: Sat Feb 18, 2006 10:36 am    Post subject: You think alternators are safe? Reply with quote

Hi Bob,
Are the miniature DSP circuit breakers available at
this time and how much would you expect them to cost?
Bob Sultzbach

--- "Robert L. Nuckolls, III" <nuckollsr(at)cox.net>
wrote:

Quote:

Nuckolls, III" <nuckollsr(at)cox.net>

At 06:50 AM 2/17/2006 -0800, you wrote:

>
Frank George (Corvallis)"
><frank.hinde(at)hp.com>
>
>I think this means...Fusable links can start a fire
before the fuse
>blows?....Smile
>
>Therein lies the problem with 12V power presumably.
>
>Frank
>
> If this is interpreted to be a requirement,
then it cannot
> be complied with using contemporary
I(squared)*R overcurrent
> detecting devices; I.e., thermal breakers, fat
fuses or
> ANL limiters and particularly fusible links.
>
> Bob . . .

This isn't a system voltage or DC versus AC
issue. This is
a hard fact of physics in all power systems.
The paragraph
I cited from AC43-13 completely ignores the
"soft fault"
phenomenon that may occur at any voltage level,
any current
level and in AC or DC systems.

Example: A C-90 on short final to Clovis NM
about 1990 was
suddenly stricken with complete disconnect of
control in pitch.
Elevator forces in wheel went to zero. The
pilots did a go around
and managed to land safely with power and pitch
trim.

A teardown revealed a mis-positioned wire
bundle under the
floorboards where a 40A protected wire for
co-pilot's windshield
heat had had been rubbing against the elevator
cable for some
period of time.

No smoke, no fire, no flickers in the
electrical system, no
trips of the 40A breaker. Over the pre-failure
interval,
megajoules of energy were released in the
erosion of steel
wires (the copper wire was in pretty good shape
. . . this
demonstrates why layers of copper are included
in the design
of safes . . . nearly impossible to penetrate
with a cutting
torch).

In other instances, it's easy to imagine a
10-cent resistor
burning up in a radio and making lots of nasty
smells in the
cockpit while failing to open a 5A fuse that
protects the
feed wire to the failed device.

Bottom line is that ALL thermally actuated
protective devices
(fuses, heater actuated breakers, current
limiters, fusible
links) and even magnetic breakers are incapable
of reacting to
the low-rate, long-duration soft faults that
are exemplified
by the two scenarios I offered above. This
illustrates the silliness
of any designer (or bureaucrat) who believes
that AC43-13/11-48
can be complied with.

Since the Swiss Air 111 accident, there has
been
a lot work to develop miniature breakers fitted
with little
digital signal processing receivers designed to
listen for
and react to unique signal characteristics of a
low current
electrical arc. These probably won't keep
10-cent resistors
from smoking but they WOULD have prevented
damage to the
C-90's elevator cable and probably would have
prevented the
Swiss Air 111 incident.

It's the system designer's goal to UNDERSTAND
the technology
behind products he/she includes in the system
and in particular,
limits that are not articulated in spec sheets.

Bob . . .





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PostPosted: Sat Feb 18, 2006 12:42 pm    Post subject: You think alternators are safe? Reply with quote

Quote:
A teardown revealed a mis-positioned wire bundle under the
floorboards where a 40A protected wire for co-pilot's windshield
heat had had been rubbing against the elevator cable for some
period of time.

No smoke, no fire, no flickers in the electrical system, no
trips of the 40A breaker.

Allow me to publicly display my ignorance.....isn't there some form of
GFI that would sense the difference between the hot and ground
and trip the circuit? I know the stated standard for UL is 5ma (like
that applies here!) so that wouldn't work but, say, some larger level
of leakage detection? Or would this be a trippin' son-of-a-gun with all
the impulse loads we generate?

Jim Baker
580.788.2779
'71 SV, 492TC
Elmore City, OK


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nuckollsr(at)cox.net
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PostPosted: Sat Feb 18, 2006 1:22 pm    Post subject: You think alternators are safe? Reply with quote

At 02:38 PM 2/18/2006 -0600, you wrote:

Quote:


> A teardown revealed a mis-positioned wire bundle under the
> floorboards where a 40A protected wire for co-pilot's windshield
> heat had had been rubbing against the elevator cable for some
> period of time.
>
> No smoke, no fire, no flickers in the electrical system, no
> trips of the 40A breaker.

Allow me to publicly display my ignorance.....isn't there some form of
GFI that would sense the difference between the hot and ground
and trip the circuit? I know the stated standard for UL is 5ma (like
that applies here!) so that wouldn't work but, say, some larger level
of leakage detection? Or would this be a trippin' son-of-a-gun with all
the impulse loads we generate?

There are ground fault detection devices for DC systems but
they're complex and of limited usefulness. We use them on
major feeders in aircraft but they would never be used in
situations like the soft faulted windshield heater line
I cited.

Some components of the system are installed with attention
to detail that makes over load and ground fault protection
unnecessary. In the case of the windshield heater wire, good
practice was ignored in the restoration of the airplane to
proper configuration after a maintenance event. By the way,
I came across this incident during a search of accident records
at RAC looking for relative numbers of electrical systems issues
that started a chain of events leading to an accident. They
are exceedingly rare and in this case, didn't result in
damage to airplane or occupants. It was an interesting data
point but in no way intended to raise concerns on anyone's
part that we should be looking for the next greatest advancement
in aircraft safety. Hmmmm . . . I'd better not say that too
loud. The FAA just might pick that up as the the next cause du jour.
Bob . . .


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PostPosted: Sat Feb 18, 2006 1:30 pm    Post subject: You think alternators are safe? Reply with quote

At 10:35 AM 2/18/2006 -0800, you wrote:

Quote:


Hi Bob,
Are the miniature DSP circuit breakers available at
this time and how much would you expect them to cost?
Bob Sultzbach

Not that I'm aware of. But even if they were, I wouldn't
recommend them. The fuseblock delivers the highest cost-
benefit ratio for wire protection we can buy.

The people who NEED them are the poor saps that bought
air transport class aircraft wired with Kapton insulated
wire. I knew how bad this stuff was when I had the electrical/
avionics group on the GP-180 25 years ago. We opted for Tefzel
back then as did all the Wichita OEM's.

The big airplanes cannot be rewired. Further, the amount of
lint (almost explosive) and other trash that builds around
the innards of old airplanes makes arc-tracking in Kapton
wiring a much more serious issue. The "fix" is to replace
breakers with devices that will detect arcing soft failures
in the wires. This is not a concern for OBAM aircraft where
builders have installed the best . . . Tefzel.

Bob . . .


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