CONVERSION OF A DOL MOTOR TO VFD STARTER

I have a 3.3 KV motor with following details-
Duty S1
Insulation Class/Temp Rise: F/B
KW: 450
Type of Starting as per name Plate: DOL
Stator Connection: Star
Full Load Current: 93 A
Starting Current: 558 A
Starting Torque: 70% of FLT
Pull Out Torque: 205% of FLT
FLT: 295 KGm
Insulation: VPI

Please advise

1. Can I run this motor on VFD? What would happen if i do this?
2. If I dont use a VFD and run the 2 motors on DOL, what would be current requirement at Breaker side?

REGARDS
 
I have a 3.3 KV motor with following details-
Duty S1
Insulation Class/Temp Rise: F/B
KW: 450
Type of Starting as per name Plate: DOL
Stator Connection: Star
Full Load Current: 93 A
Starting Current: 558 A
Starting Torque: 70% of FLT
Pull Out Torque: 205% of FLT
FLT: 295 KGm
Insulation: VPI

Please advise

1. Can I run this motor on VFD? What would happen if i do this?
2. If I dont use a VFD and run the 2 motors on DOL, what would be current requirement at Breaker side?

REGARDS
M

the answer to your first question is Yes……and No.

If you were to connect your motor to a VFD rated at 3.3KV and 450 KW, the motor would start and run. However you would have three tremendous problems. These are:

1. The VFD would generate high voltage transients at a rate of 1 to 4 KHz. These transients would eventually damage your motor. You need to have either a VFD which is designed to clip these transients, or an inverter rated motor.

2. The VFD would develop high power harmonics which would damage both the VFD and other electronic components connected to the same power lines. You will require special VFDs which are designed to reduce these transients, and which are very expensive.

3. Code requires that the power leads to the VFD be designed based on the rated current of the VFD, and not the rated current of the motor. This could cause you to rework your motor branch circuit

Regarding your second question. I do not recommendDOL starting two motors this size in parallel.

I hope this helps.
 
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