On Thu, 3 Oct 1996, Steven A Eberhart wrote:
> On Thu, 3 Oct 1996, Tom Riley wrote:
>
> > I'm far from needing switches for my instrument panel
> > yet, but I have looked at some of the readily available
> > circuit breakers and have one concern about a popular
> > model made by Potter-Brumfield. If anyone could comment
> > on the following, it would be much appreciated.
> >
> > The P-B W31 series (thermal breaker with built-in toggle)
> > seems to be very susceptible to being fliped OFF by shock -
> > and it doesn't take much. Try it, take a W31 and set it to
> > the ON (up) position, then hold it upright in your right
> > hand with the toggle away from you and strike the palm of
> > your left hand. It doesn't take too much of a blow to flip
> > the switch to the OFF position.
> >
> > It would seem to me that a good bang in bad turbulence
> > could result in shutting off several such breakers --- not
> > fun. Does anyone have any experience with these breakers
> > or care to comment? Am I way off base here, or is this a
> > valid concern?
> >
>
> I designed the original test equipment used to test the P&B thermal
> circuit breakers. Just the electrical test, not impact or vibration. It
> has been thirteen years since I left the company but their engineering
> offices are just thirty minutes up the road. I will see if any old
> friends are still around and try to get a response to the impact
> question.
>
> Steve
>
I just got off the phone with an old friend that still works at P&B and
got the following information.
1. The W31 breakers are not now specified in reguards to shock
tripping. The old spec. used to be 15 to 25 G's. The low Amp. breakers
up to about 4 Amps were good for 15 G's, above 4 Amps were good for 25
G's. Rapping on your hand is not a valid test.
2. From date code 9550 to present should be returned to your supplier
for replacement!!!! There is a manufacturing defect that has, as of
today, not been corrected. When the breakers trip, they can NOT be
reset. Breakers made before date code 9550 should be OK.
Just passing along the information I was told by the now anonymous source.
Steve
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