I was looking for some more information on applying a single phase input (power supply) for 3 phase VFD. I have been beating my head on this for weeks now, I have done some basic math (on derating the drive for single phase power input), and I am now at the point where I want to tell the customer to go with a single phase 240 V motor.
The basic synopsis of the customer's needs are as follows:
- The customer only has 240 V Single Phase, 200 A Service.
- The customer needs 3 Phase 240 V or 480 V to drive a 240 V/460 V, 76/37 FLA, 60 Hz, 1755 RPM, 0.875 P.F. Motor (to drive a pump for a hydraulic compressor).
- I have supplied the customer with a 60 HP VT Variable Frequency Drive, which is as follows:
77 A Input Current, 87 A Input Current
380-500 V Input Voltage
0-500 V Output Voltage
The Problem:
I obviously do not have enough input voltage available from the Customer's Service Panel.
I - think I - need at least 480 V input voltage and at least the available input current of the drive (77 A) to run the motor somewhat efficiently.
I do realize that I will not be getting near the DC Bus Voltage (with single phase power input) since only half the inverter section with be getting AC input. So, there will need to be a substantial amount of input power available to compensate.
My question is: Can I use a single phase 240 V to 480 V Transformer (or even a single phase 480 V to 240 V transformer, by back-feeding 240 V through the secondary to get 480 V out of the primary) with at least 77 A available from the transformer?
Or in other words, would I need a transformer KVA Rating of: (77 A x 480 V)/1000 = 36.96 or 37 kVA?
I also realize that this seems quite complicated and silly to be doing but, I purchased the drive for a good price and would like to get it to work.
Any help at all would be greatly appreciated.
The basic synopsis of the customer's needs are as follows:
- The customer only has 240 V Single Phase, 200 A Service.
- The customer needs 3 Phase 240 V or 480 V to drive a 240 V/460 V, 76/37 FLA, 60 Hz, 1755 RPM, 0.875 P.F. Motor (to drive a pump for a hydraulic compressor).
- I have supplied the customer with a 60 HP VT Variable Frequency Drive, which is as follows:
77 A Input Current, 87 A Input Current
380-500 V Input Voltage
0-500 V Output Voltage
The Problem:
I obviously do not have enough input voltage available from the Customer's Service Panel.
I - think I - need at least 480 V input voltage and at least the available input current of the drive (77 A) to run the motor somewhat efficiently.
I do realize that I will not be getting near the DC Bus Voltage (with single phase power input) since only half the inverter section with be getting AC input. So, there will need to be a substantial amount of input power available to compensate.
My question is: Can I use a single phase 240 V to 480 V Transformer (or even a single phase 480 V to 240 V transformer, by back-feeding 240 V through the secondary to get 480 V out of the primary) with at least 77 A available from the transformer?
Or in other words, would I need a transformer KVA Rating of: (77 A x 480 V)/1000 = 36.96 or 37 kVA?
I also realize that this seems quite complicated and silly to be doing but, I purchased the drive for a good price and would like to get it to work.
Any help at all would be greatly appreciated.