Today's Message Index:
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1. 08:24 AM - Re: Strobe switches (Robert L. Nuckolls, III)
2. 08:29 AM - Strobe switches? (Dr. Andrew Elliott)
3. 09:28 AM - Re: Strobe switches (Bill Watson)
4. 10:30 PM - Re: Digital Industrial Scales Outlets (Andrew29)
Message 1
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Subject: | Re: Strobe switches |
> The strobe switch is backed up by a 7 amp fuse which is
> recommended for the strobe system (Whelen) and it has never popped.
> The run of 18 ga. wire is about ten feet. Of all the switches, only
> the strobe switch gets real hot after only a few minutes of use.
Can you tell where it's getting hot? We've
had this (and similar) discussions on strobe
controls over the years. I am mystified as
to how the burning of switches and terminal
crimps seems to be concentrated on the strobe
systems . . . driven by relatively light
protection (7A fuse).
>I was searching B&C for a relay I could use to reroute the strobe
>heavy current wire, and discovered that B&C now advertises a MilSpec
>single pole switch (MS35058-22) that is the equivalent of the
>S700-1. The dimensions appear the same, with screw type connections
>rather than fast ons. It ain't cheap, but it would be worth it to
>avoid having to frequently replace a burnt out standard switch.
>Would this MilSpec switch be a viable solution to the strobe switch problem?
Your question raises some interesting points.
There seems to be something 'different' about
the strobe system current draw profile that
stresses the centers of highest-resistance
in the power path. In the past, we've seen
failures at the rivet joints on the switches,
contacts within the switches, switch rockers,
and less-than-idea crimps on terminals, etc.
Yet the RMS or average current remains so
low that a relatively fast protective device
like a fuse doesn't complain. I would REALLY
like to see the current profile on a strobe
system that has repeatedly damaged its switch.
There's got to be a characteristic unique to
strobe supplies (perhaps just this model
of supply) that's especially antagonistic
to components in the power feeder.
Getting to your specific questions. A
relay would certainly transfer the stresses
away from the switch . . . but any connecting
devices in the power path (like crimps)
would still see the 'abuse'.
It might well be that a switch with molded
terminal supports . . .
Emacs!
. . . would not offer the weaknesses of
riveted joints . . . but crimps, threaded
fasteners and internal contacts of the
switch would still be getting 'hammered'.
I do have a proof-of-concept, solid state
relay that I'd be pleased to send you. I've
like to get it into service on an often-flown
airplane and perhaps yours is the best
candidate. It appears that the strobes feeder
in your airplane would be a good location to
try the relay while potentially addressing
your specific failure mode.
Do you have access to any test equipment
that might measure and record the current
waveform impressed on the strobe switch
in your airplane?
I'm mulling over ideas for getting data
of your airplane and then perhaps expanding
the investigation to other airplanes to
see if we can identify the controlling
physics.
There are tens of thousands of airplanes
flying Carling switches in the strobe
power feed path . . . the fact that a
few folks here on the List have experienced
serial failures of these switches is
curious to say the least.
Bob . . .
Message 2
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Subject: | Strobe switches? |
Following some FMEA principles might be valuable here, yes? First,
you have some evidence that it is *not* a switch problem, since various
switch replacements have done nothing to alleviate the issue. Second,
many thousands of builders have strobes in their aircraft which have no
problems with switches and fast-on wires burning up. Together, these
would tell me to look elsewhere for the root cause.
Do you have a non-standard strobe power supply? Can you swap it with
a friends to see if that makes any difference? Can you bench test it
using ground power?
Are you using unusual strobe bulbs? Are they the correct bulbs
specified for the power supply and fixtures? Are you using an unusual
flash pattern? Perhaps with a high duty cycle?
Is there any other evidence of higher than expected current flow
behind the switch panel? Other switches or wires? Voltage regulator?
Is the ground for the strobe circuit solid?
FWIW,
Andy
------------------------
Andy Elliott, CL:480-695-9568
N601GE/Z601XL/TD/Corvair
555 hrs since 11/08
<http://servi-aero.com/n601ge/4sale/> Web Site Link
Message 3
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Subject: | Re: Strobe switches |
I experienced a burned out fast-on connector at my fuse panel on the
16AWG strobe power lead between the fuse panel and the switch. My
strobe unit was a CreativAir Avi-Pak 60 watt, 4 outlet strobe power
suppy intended for experimental aircraft use. Three strobes were
connected. There was a 15amp fuse on the unit and a 15amp fuse on the
fuse panel. This was on an RV10 and there was somewhere between 10 and
20 feet of 16AWG wire in the switched power circuit.
I had difficulty identifying the burned out fast-on connector. The
circuit remained intact despite it's inability to carry the required
load. In the course of problem determination, I decided to replace the
unit. (I later determined that the unit works just fine)
The CreativAir units are no longer available so I installed a unit from
Nova Electronics - XPAK604X 60 watt, 4 outlet strobe power suppy. It is
also referred to as a SUPERPAK604X. This unit seems to be intended for
emergency vehicle use but is very similar to the CreativAir product, it
looks like it is from the same manufacturer with the same dimensions and
mounting hardware.
However, it can be powered by an unswitched line directly from the power
circuit. It is operated thru a separate control circuit. In the RV10
this allowed me to reduce the power circuit from over 10 feet to less
than 3 feet. Where the old circuit was warm/hot to the touch,
everything is now cool.
The XPAK604X was cheaper, had more strobe pattern options and used a
control circuit which would seem to accomplish what a relay would do.
On 1/21/2014 2:19 AM, B Tomm wrote:
>
> What about using a relay to switch the strobe current? Use the carling
> switch to control the relay.
>
> Bevan
>
> -----Original Message-----
> From: owner-aeroelectric-list-server@matronics.com
> [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Charles
> Brame
> Sent: Monday, January 20, 2014 9:33 PM
> To: List AeroElectric
> Subject: AeroElectric-List: Strobe switches
>
> --> <chasb@satx.rr.com>
>
> Bob, et.al.,
>
> I just replaced my fourth S700-1(or equivalent) strobe switch in about 200
> hours of flying time. Both fast on terminals were badly burned as was about
> an inch of the 18ga. wire attached to the fast on. My first two switches
> were Carlings from B&C. Based on AeroElectric recommendations made some
> years back, I ordered a S700-1 equivalent switch from Honeywell - same
> result. Then I tried a switch from DigiKey, same result. I'm back to a
> Carling, at least for the short term. I have Carlings for the Nav lights,
> Landing and Wig Wag lights and instrument lights, and I have had no problem
> with any of them. The strobe switch is backed up by a 7 amp fuse which is
> recommended for the strobe system (Whelen) and it has never popped. The run
> of 18 ga. wire is about ten feet. Of all the switches, only the strobe
> switch gets real hot after only a few minutes of use.
>
> I was searching B&C for a relay I could use to reroute the strobe heavy
> current wire, and discovered that B&C now advertises a MilSpec single pole
> switch (MS35058-22) that is the equivalent of the S700-1. The dimensions
> appear the same, with screw type connections rather than fast ons. It ain't
> cheap, but it would be worth it to avoid having to frequently replace a
> burnt out standard switch. Would this MilSpec switch be a viable solution to
> the strobe switch problem?
>
> Charlie Brame
> RV-6A, N11CB
> San Antonio
>
>
Message 4
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Subject: | Re: Digital Industrial Scales Outlets |
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Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=417393#417393
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