Re: Interesting relay failure

From: Bob Tom (tigers@bserv.com)
Date: Wed Sep 08 2004 - 09:18:59 EDT


At 12:07 AM 9/8/04, you wrote:
>When a tamping diode is part of the relay, which should be the positive for
>the trip? 85 or 86? TonyC

Tony, I'm by no means an expert with relays. My son has just recently
completed
retraining into the field of electronics.

It's my understanding that the only thing that changes when using a tamping
or quenching diode is the fact that the positive terminal and the striped end
of the diode MUST BE together. The positive control lead should NOT be
connected to the unstriped (anode) end of the diode because there will
effectively be a short circuit to ground, possibly causing damage to the
control
circuit (if the control circuit is not properly fused).

HTH. Let me know if it doesn't and I'll try to get answers to any questions
that you may have from my son.

BTW, there are some relays with internal suppression circuits which make
the external diode unnecessary. The suppression circuit is generally a
resistor or a diode parallel to the relay coil. I would guess that there would
be instructions/directions as to where to hook up the positive, otherwise
the relay may be damaged or in some cases simply won't operate.

Bob



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