Single phase to 3 phase with capacitors

[Jeff80]

How would I size capacitors for a 6 hp pump that is 3 phase when I only have single phase power at my control panel.

Also how would the schematic look for the install with a start cap and then caps for the 3 phase.

 

[Rick Christopherson]

What you are suggesting is a static converter, but I would not recommend it for a pump application if the pump is operating anywhere near full load.

If you want to build a static converter, there are plans on my web site to do so, and I strongly suggest you take the time to properly balance the capacitors as described. Any design that does not include a second set of run-capacitors is a poor design and should be avoided. You can ignore the information about building your own voltage-sensing relay and purchase a proper voltage-sensing relay, which are commercially available.

http://www.waterfront-woods.com/Articles/phaseconverter.htm

For your application, I would suggest using a VFD instead of a phase converter. To power it from single-phase power, you simply over-size the converter by 1.7 times the rated output. The VFD takes incoming power and converts it to DC before creating a 3-phase signal. The need for derating is because the input rectifier is not as efficient on single-phase as it is on 3-phase.

 

[Cow]

For your application, I would suggest using a VFD instead of a phase converter. To power it from single-phase power, you simply over-size the converter by 1.7 times the rated output. The VFD takes incoming power and converts it to DC before creating a 3-phase signal. The need for derating is because the input rectifier is not as efficient on single-phase as it is on 3-phase.

Then he could wire in a pressure transmitter to the VFD for maintaining system pressure, if needed.

 

[Jeff80]

Thank you for the help...

This was for a lift station with a two pump alternating setup.