I am looking to set up a E-buss system with standby alternator and one battery. I would like to use a relay where if the power is OFF on the control circuit (Main Bus) the load circuit (E-buss) comes ON. Is there such a thing? Lamar Superswitch has a "negative" version but that closes if the control earths - not quite what I need.
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Power Off Relay
- Thread starter paul330
- Start date
fl-mike
Well Known Member
Paul,
It sorta sounds like you are looking for a SPDT relay operating as a transfer switch with the coil connected to your main bus. If the main bus drops, the relay opens and connects to the NC contact.
That being said, I would consider a couple of steering diodes/rectifiers instead of a relay.
It sorta sounds like you are looking for a SPDT relay operating as a transfer switch with the coil connected to your main bus. If the main bus drops, the relay opens and connects to the NC contact.
That being said, I would consider a couple of steering diodes/rectifiers instead of a relay.
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I know that the Aeroelectric method is to use a diode but that requires the secondary wire to the E-buss to be permanently connected. For some reason, I just don't like that idea. It could be switched but then there would be a delay with no power momentarily. My idea would be the relay with an ON-AUTO-OFF switch to bypass the relay if needed. I know it would work well - it's just a case of finding a relay. They exist in the commercial world but I need to find one at experimental prices!
To clarify, with power in the switching circuit (in this case, the main buss) the contacts on the power circuit (E-buss standby wire) are held open. If power fails (ie loss of main buss) the contacts close and the E-buss is powered by its' secondary route.
If I knew how to do it, I could post a diagram!
To clarify, with power in the switching circuit (in this case, the main buss) the contacts on the power circuit (E-buss standby wire) are held open. If power fails (ie loss of main buss) the contacts close and the E-buss is powered by its' secondary route.
If I knew how to do it, I could post a diagram!
fl-mike
Well Known Member
25A. I think I have found what I need at Maplins (UK Radio Shack). It was "SPDT" that was the key to tracking it down. I just need to make sure it is continuous duty. Cost is less than $10
There are plenty of the "ice-cube" SPDT relays that will handle that. Bosch/Tyco/Potter & Brumfield have some impressive offerings. You could likely pop one out of your car if you wanted to experiment.
http://order.waytekwire.com/productdetail2/M37/75312/RELAYS%20HIGH%20CAPACITY%2012V%20SPDT/
Sounds like you found something though.
