Two twin DC motors that have very different full load armature amps

[Hoosierken]

We are a large electric motor shop. We received from a customer two allegedly identical motors, 150HP Stabilized shunt motors.
Under a full load of 150HP and 1800 RPM the armature current is drastically different.
#1 motor armature amps-269
#2 motor armature amps-126
#1 motor tested stable.
#2 motor was much more sensitive to load and difficult to stabilize load.
Are we looking at interpoles that may have been incorrectly rewound?
Something else?
Ken

 

[synchro]

You could check whether the series winding is connected with the same polarity relatve to the shunt winding in both motors. The wrong polarity on the series winding would make it oppose the magnetic field of the shunt winding, causing a higher armature current and likely making it less stable. However, in your case the motor with the higher armature current is more stable. But I think it's still worth verifying that the internal winding connections are the same on the two motors.

 

[ptonsparky]

For my curiosity, what should the current be?
This way above my pay scale otherwise.

 

[Hoosierken]

For my curiosity, what should the current be?
This way above my pay scale otherwise.

For my curiosity, what should the current be?
This way above my pay scale otherwise.

Armature current should be 240 but we are only seeing 120 at full load. We are leaning on incorrect interpole connections. Maybe parallel but should be series. We only recieved the motor to perform load test only. So, motor is no longer in our shop.

Thanks for the ideas.