09-12-2016, 08:51 PM
I discovered that I had a issue with each contactor that may not have been an issue if they had been used alone or in another application. And I now understand how they work and why the transfer interlock switch should NEVER be bypassed.
To recap, I replaced both original contactors with new ones. Contactor "A" was the one and attached to shore power: Contactor "B" was the one attached to generator. After I installed them, fuses blew whenever I flipped the switch above the driver to select a power source. I called Newell and they determined that both contactors were wired correctly but they just didn't know what to tell me.
One problem was relatively easy to solve when I found low resistance in the coil of contactor "B," which I figure caused the fuse blowing.
What wasn't so easy to find was why when I flipped the switch to generator above the driver, nothing would happen. The switch sent power back to the transfer interlock switch on contactor "A", but the interlock would not engage and send power to the coil on contactor "B."
That's when I started asking questions here about connecting directly to the coil and by-passing the transfer switch.
I disassembled the transfer interlock switch from the old contactor just to see how it worked. Let me tell you, there is not much there, which only made the mystery more mysterious to me. I then took out the interlock switch from contactor "A" and disassembled it too. The two were pretty much constructed the same except for one almost unnoticeable difference. The transfer interlock switch required in my application has part in it that when contactor "A" is engaged, it pulls it up and the transfer interlock switch creates an open circuit that prevents power from energizing the coil on contactor "B". But the part in that particular interlock did just the opposite. When contactor "A" was engaged, it pulled it up but closed the circuit. Then when contactor "A" disengaged, it dropped it back down but, instead of being closed, it created an open circuit that stopped power from getting to the coil on contactor "B."
I'm sorry if all this sounds confusing, but the end result is that after I installed the old transfer interlock switch, everything pertaining to this problem now works as it should. Now there's issues with the air pressure system ;-(
To recap, I replaced both original contactors with new ones. Contactor "A" was the one and attached to shore power: Contactor "B" was the one attached to generator. After I installed them, fuses blew whenever I flipped the switch above the driver to select a power source. I called Newell and they determined that both contactors were wired correctly but they just didn't know what to tell me.
One problem was relatively easy to solve when I found low resistance in the coil of contactor "B," which I figure caused the fuse blowing.
What wasn't so easy to find was why when I flipped the switch to generator above the driver, nothing would happen. The switch sent power back to the transfer interlock switch on contactor "A", but the interlock would not engage and send power to the coil on contactor "B."
That's when I started asking questions here about connecting directly to the coil and by-passing the transfer switch.
I disassembled the transfer interlock switch from the old contactor just to see how it worked. Let me tell you, there is not much there, which only made the mystery more mysterious to me. I then took out the interlock switch from contactor "A" and disassembled it too. The two were pretty much constructed the same except for one almost unnoticeable difference. The transfer interlock switch required in my application has part in it that when contactor "A" is engaged, it pulls it up and the transfer interlock switch creates an open circuit that prevents power from energizing the coil on contactor "B". But the part in that particular interlock did just the opposite. When contactor "A" was engaged, it pulled it up but closed the circuit. Then when contactor "A" disengaged, it dropped it back down but, instead of being closed, it created an open circuit that stopped power from getting to the coil on contactor "B."
I'm sorry if all this sounds confusing, but the end result is that after I installed the old transfer interlock switch, everything pertaining to this problem now works as it should. Now there's issues with the air pressure system ;-(