Tony Wells
Senior Member
Thanks for the explanation, Birken. I'll run a few more tests Monday and see what I can turn up. I won't be working on it over the weekend, other than mentally. If another test should cross your mind, please don't hesitate to note it here.
So basically if the exciter is working (and it is) to generate some voltage on the final output, the power for the AVR is coming from the Aux windings, and it seems to be or there would not be 26 volts on the exciter terminals (d/c), then something may be related to the sensing circuit. If that was having problems it would kill the exciter voltage....but it doesn't, unless the primary field coil is connected. Seems very odd to me. I'm no stranger to electricity or electronics, but I haven't gained a full grasp of this method of regulation/generation yet. With everything connected, the main output is a measly 16-18 volts (not truly zero).....so maybe there is a false flag sent to the AVR by the sense circuit causing to fall off. IIRC, there are toroids that each of the three legs go through just above the main breaker. Seems they are labeled "load sense". Can hardly see how they could fail. But I'll check them.
So basically if the exciter is working (and it is) to generate some voltage on the final output, the power for the AVR is coming from the Aux windings, and it seems to be or there would not be 26 volts on the exciter terminals (d/c), then something may be related to the sensing circuit. If that was having problems it would kill the exciter voltage....but it doesn't, unless the primary field coil is connected. Seems very odd to me. I'm no stranger to electricity or electronics, but I haven't gained a full grasp of this method of regulation/generation yet. With everything connected, the main output is a measly 16-18 volts (not truly zero).....so maybe there is a false flag sent to the AVR by the sense circuit causing to fall off. IIRC, there are toroids that each of the three legs go through just above the main breaker. Seems they are labeled "load sense". Can hardly see how they could fail. But I'll check them.