Recent content by edison123

Is that a stator - rotor rub? Aluminum die-cast rotor? Speed?

"We are bit sure that the problem is in rotor laminations because a similar motor with the same symposium was deconstructed and found a deformation in it’s lamination." What kind of deformation? Post some pictures and complete motor nameplate.

"The VFD acts as the filter". How? why not go for a 690 V motor of same size? standard VFD and reduced cable size.

Looks like the top mcb is the output with output voltmeter connected. The connector terminal blocks seem to be unfit for load output. Zero nameplate details. OP has to engage to more

Great info, Gianoli. 33,500 A ? :oops:

Who is making 15,000 amps breakers? The maximum I am aware of is 5,000 amps VCB. Large generators have the breakers on the HV side of the generator step-up transformers.

Post the motor capacity first.

Thanks jeff. The client says the VFD was in V/Hz mode and the current sharing was almost equal. After the ID run, the motor overheating is gone, and it is running well now. Still don't know how the overheating started and then was gone. gra8blu - It's a standard random winding with just more...

Bill - This is not VFD, it's good old MG set. No harmonics. I do have some moving coil reciter type meters somewhere in our inventory. Time to root them out and see if they work at low Hz.

Both motors drive the same load via a single VFD. VFD details not available at the moment. The new winding is VFD duty rated (which is anyway voltage related and not current related). jeff - Isn't the very idea of V/Hz is to keep the flux density constant without going into saturation at any...

You need the right capacitor and the right input volts of 110 V, 60 Hz. I don't see a capacitor. Great ammeter. We don't get such 330 deg meters anymore.

Thanks jeff. Yes, I understand the challenge of low Hz volt and amp measurements. I do have the good old d’Arsonville analog voltmeter somewhere. Let me check.

Thanks all. But why would tuning / not tuning the drive or whatever mode affect the motor winding temperature so drastically?

Single VFD running two 400 HP AC motors driving on-shore oil drill via gears. One motor is original winding and one was rewound with 10% more copper area and hence 10% lower DC resistance. Both the motors had the same inductance since the turns are the same. Upon recommissioning, the rewound...

The standard cold rolled steel are designed for 60 Hz for the real world. For higher frequencies like aircraft 400 Hz, special thin amorphous core is needed due to hysteresis loss and eddy current loss. Those cores are mighty expensive.