VFD Question

[Web Goblin]

Single phase 220v to 3 phase 415 volt inverters are available if you have deep pockets, a 3HP one will cost you around £500.

[Chaz]

Single phase 220v to 3 phase 415 volt inverters are available if you have deep pockets, a 3HP one will cost you around £500.

Well, the unit bought up above was £650 2nd hand. They sell for >£1K typically for 5HP.

[m_c]

Rotary phase converters work by using a three phase motor, and powering it on two legs from single phase. The third phase is then generated by the motor. Capacitors are added to help balance the third phase voltage, and for starting (very large rotaries may use a smaller single phase pony motor for starting).
There are plenty guides about if you google for them.

I run my workshop from one, which simply adds a 240-380V transformer to the mix, so I get three phase at the more common UK three phase voltage.

They do use power when running, but certainly not enough to justify the cost of changing to some form of digital inverter. I did price one, and I think I'd have to run the rotary constantly for several years before a digital inverter would pay for itself.