Use VFD rated motor for DOL start

[Amir]

Good Day.
We currently have 4260HP motor which is fed and run thru VFD.
Now, we are in urgent need to use this motor as the VFD is damaged beyond repair.
Question, can we supply and start this motor DOL.
Out put of VFD is 4160V, so we want to connect to 4160 source and start across the line.
What do you guys think?

 

[kwired]

Good Day.
We currently have 4260HP motor which is fed and run thru VFD.
Now, we are in urgent need to use this motor as the VFD is damaged beyond repair.
Question, can we supply and start this motor DOL.
Out put of VFD is 4160V, so we want to connect to 4160 source and start across the line.
What do you guys think?

Can the POCO provide surge capacity needed for across the line starting is likely the #1 item to consider.

Even if they can, are they willing to allow it is #2 item.

At very least I bet you will need some sort of reduced voltage starting method.

 

[Jraef]

Running on a VFD is harder on the motor insulation in terms of voltage stress, but otherwise, it's the same so yes, you'll can start it DOL. But pay heed to kwired's issues, and I'll add that you should thoroughly investigate the starts-per-hour capability of that motor as well. Starting it with a VFD puts less thermal stress on the motor, starting it DOL causes significantly more. You may find it can only be started once or twice per hour, so just make that an issue with your DOL starter, as in using a restart delay timer.