EcoRenovator - View Single Post - ice storm, generators and lessons learned

oil pan 4 · 01-13-16, 11:45 AM

You don't want to run VFD on single phase.
Typically for high starting torque motors you use capacitor start. Capacitor start uses a mechanical centrifuge to turn the start circuit on and off. During run up the start circuit does not cut out until the motor is almost at operating speed.
If the motor runs for more than 5 or 10 seconds with the start circuit powered up it will fry something in the start circuit, usually the capacitor or the windings.
If you drop the motor speed down too low the start system will reengage, frying the starter.

This is why industrial pumps are pretty much always use 3 phase inverter duty rated motors connected to VFDs. The motors and what ever they drive can be soft started and ran at variable speed, usually any speed between 20hz and 60hz. Some VFDs can produce 100hz.
You can get a 3 phase VFD that can be powered single phase 240vac power.

01-13-16, 11:45 AM	#26
oil pan 4 Land owner Join Date: Nov 2012 Location: NM Posts: 1,026 Thanks: 12 Thanked 127 Times in 107 Posts	You don't want to run VFD on single phase. Typically for high starting torque motors you use capacitor start. Capacitor start uses a mechanical centrifuge to turn the start circuit on and off. During run up the start circuit does not cut out until the motor is almost at operating speed. If the motor runs for more than 5 or 10 seconds with the start circuit powered up it will fry something in the start circuit, usually the capacitor or the windings. If you drop the motor speed down too low the start system will reengage, frying the starter. This is why industrial pumps are pretty much always use 3 phase inverter duty rated motors connected to VFDs. The motors and what ever they drive can be soft started and ran at variable speed, usually any speed between 20hz and 60hz. Some VFDs can produce 100hz. You can get a 3 phase VFD that can be powered single phase 240vac power.