What does a voltmeter indicate if the positive field lead between a generator and a control panel breaks and shorts while the engine is running?

When the positive field lead between a generator and a control panel breaks and shorts while the engine is running, the voltmeter indicates residual voltage. In this situation, the generator may still produce a certain amount of voltage due to the residual magnetism present in the alternator or generator.

Residual voltage is the small amount of voltage that remains when a generator is not being externally excited. This residual magnetism allows a limited voltage to be registered on the voltmeter even though the positive field lead is compromised. Essentially, the electrical path has been disrupted, but the magnetic fields within the generator still optimize to produce some form of output voltage until the generator's operation is completely affected.

Continuous voltage supply and intermittent voltage do not accurately describe the scenario, as those suggest a stable or fluctuating source directly linked to external excitation, which is not the case here. Zero voltage would also not apply, since the residual magnetism would prevent total voltage loss at that moment even if the system isn't functioning properly. Thus, the indication of residual voltage reflects the system's compromised condition without complete failure.