Interesting power problem 2

[EE7860]

I have an interesting question if any one can help.
2 identical compressor motors with the following data.
600HP, 2300V, 390RPM, 152FLA
Both were run uncoupled to check the amps.

One being fed from Delta-Wye transformer with the following data
12470V-2400Y/1383
2000/2240(OA) KVA, %Imp 5.24, transformer tap is set at 12160V. The motor running amps are approximately 104A on all three phases.

Second Transformer is Delta-Delta 13200-2400V, 1500KVA, %Imp 5.43, Transformer tap is set at 12540V. The running amps recorded are approximately 65A on all three phases.

Both transformers are ungrounded, The system voltage is 12470V. In the past motors were exchanged but the amps stayed with the transformer, in other words on Delta-Wye configuration motor pulls more amps.
Any suggestion? I thought power requirement will be the same in any case and the motors will run identical on both systems.

 

[EE7860]

Yes on Delta-Wye,one can see the voltage through multilin 469 MPR relay and it stays 2400V. This particular motor is the only load on the transformer. The Delta-Delta transformer is also 2400V. Once a year voltages are measured at the secondary of the transformers. One thing i found out is one of the motor had some failure years back and both motors were then rewound to 600HP from 350HP. I couldnt find out if this amp problem happened after the rewound or it went unnoticed even when they were run as 350HP.

 

[NAZ55]

Also, how are the two motors connected? Delta or Wye?

 

[BJC]

Are the cables the same? Shielded or unshielded?

 

[EE7860]

Motors are connected Delta, and cables are non-shielded for both motors.