Determination of windings in DC compound mtr.
Determination of windings in DC compound mtr.
(OP)
Hello,
I'm working a very old DC compound motor, 6 leads coming from the motor housing. I cannot open the motor housing, and I am trying to establish which wires go to armature, shunt field, and series field. There is also a resistor in the circuit, it is external and I assume that it is in series with the series field. I used an ohm meter to measure resistances between leads. The meter is intended for very low ohms. In doing this test, I expected to see three resistances, the shunt being pretty high, and the others less than 1 ohm. For any one lead, there should only be one other matching lead which has continuity. The others should all be open circuits. What I found was that a couple of the leads had continuity to several other leads. All of the resistances I found (7 total) were less than 0.7 ohms.
My conclusion is that the motor has some winding to winding shorts, or at least some insulation leaks. Is there any other reason that the motor leads would have multiple connections to the other leads?
The motor does run.
thanks
EE
I'm working a very old DC compound motor, 6 leads coming from the motor housing. I cannot open the motor housing, and I am trying to establish which wires go to armature, shunt field, and series field. There is also a resistor in the circuit, it is external and I assume that it is in series with the series field. I used an ohm meter to measure resistances between leads. The meter is intended for very low ohms. In doing this test, I expected to see three resistances, the shunt being pretty high, and the others less than 1 ohm. For any one lead, there should only be one other matching lead which has continuity. The others should all be open circuits. What I found was that a couple of the leads had continuity to several other leads. All of the resistances I found (7 total) were less than 0.7 ohms.
My conclusion is that the motor has some winding to winding shorts, or at least some insulation leaks. Is there any other reason that the motor leads would have multiple connections to the other leads?
The motor does run.
thanks
EE





