Ian

If all 3 motors are 380/415v 3 phase you should be able to run them all from 1 rotary inverter rated to the sum of FLC stated on all motor plates.
You may need to have the control circuit wiring/connections checked to ensure the correct voltage is provided for the contactor coils.

Emgee

Edited By Emgee on 05/10/2020 17:28:17

Just for the avoidance of confusion:-

1. Static converter:- generates a three phase supply from single phase by the use of capacitors to effect a phase shift on the generated phase. Needs adjustment of the capacitance for different loads.
2. Rotary converter:- generates a three phase supply from single phase by the use of capacitors and a rotating electrical machine to provide the generated phase. Usually does not need adjustment to cope with different loads.
3. inverter:- generates a three phase supply by rectifying the input supply to DC and then producing three phases electronically. Does not need adjustment. Can need a filter to stop noise from the supplied motors and interference with radios.

1 and 2 often have a transformer included to get 415V output from the 240V input. 3, by default produces 240V output from 240V input, but one manufacturer modify inverters to add a voltage doubler circuit, so they can produce 415V three phase from 240V single phase.

Rotary inverter:-?????

I’m no leccy, but as I see it:

Separate motors, individually controlled by the operator are no great problem for VFD operation. It is the control circuitry, two speed motor controls and the such-like that complicates things, I believe.

The advantage of individual VFDs is that each can be programmed separately. Rewiring the motors to delta, or changing individual, single speed motors to 230V three phase versions is a once-off cost. If dual voltage motors, the change-over is simply made at the motor connection terminals.

The other VFD alternative implementation is that of one large VFD – much larger than the sum of the motors – which will run any, or all, of the motors separately or at the same time. It’s often called a ‘plug and play’ installation. Normally, VFDs sized for individual motors should not be switched between VFD and the motor it drives, but if the VFD is sufficiently over-sized this is not a problem. The motors will only run just as if they were mains driven (no programming or individual protection programs)

The advantage of VFDs is that they waste very little power when not driving the motor(s).

Converters do waste power when switched on and not supplying power (rotary converters run a motor while energised) but can more easily produce the 415 volt output required for the more complex wiring of machines with inter-connected drives.

The choice is yours but clearly depends on the complexity of the machine/wiring. I would say say stay clear of the cheaper static converter suppliers. Take advice from the experts in the field – who will charge more but provide you with a reliable, working system.

For advice I can recommend;

**LINK**

Just a very satisfied customer.

Brian

Ian

Private messages sent in reply to your message to me.

Emgee