Question on Latching Relay

[richanton]

I just installed some Magnecraft 785 latching relays. The diagram indicates you apply voltage to terminal B and neutral to latch and terminal 8 and neutral to reset. I was using this with some existing relays in a room EPO circuit. What I found is that when I reset, I also was applying voltage to terminal B.
The wiring diagram shows this relay to have a single coil with internal diodes to achieve the latch. Why is there voltage on terminal B when I reset.

Here's a link to the relay diagrams.

http://www.magnecraft.com/library/section7/105A_785.pdf

 

[waross]

That's what diodes do. If you look at the diode part of the circuit you will see that the diodes are in series. If a voltage of the proper p[olarity is applied to one diode, as well as being applied to the coil the voltage/current will pass the other diode and will be seen at the other terminal as well. You must take this into acount when designing trigger circuits.
If you apply AC to one terminal, you will see half wave rectified DC at the other terminal.

Bill
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"Why not the best?"
Jimmy Carter

 

[richanton]

Thsnks for the response.

I actually had a circuit that would have worked and the electrician convinced me I didn't need it. If I take the other contact of the reset switch and put it in series with the B jumper as it jumps from the latch relays to the normal relays, I think it will solve the problem as it should open the circuit before the other contact opens.