VFD Applications need your idea

Just want to know if i can use a single inverter for 5 motors, i mean i will connect it in paraller connection but of course isolated with magnetic contactors.

I have 2 units 1HP and 3 units 1.5HP motors, driving a conveyor system I want to make some sequence for this motors and i will use only 1 VFD. The speed of the 5 conveyors are identical (constant).

Is this an ideal applications? or not. please help if this can be.


thanks...

You can run five motors from a single drive but there are a couple of issues that must be considered.

1. To size the drive, add up the motor's FLA's and add 10% for each extra motor, in your case four motors or 40%. You will need this extra ampacity to avoid overcurrent faults when starting.
2. Each motor must be protected with its own overload block with the control contacts wired in series to an external fault loop on the drive. Turn off the drive thermal overload protection.
3. Since the drive cannot see each individual motor, you must run the drive in V/Hz or open loop mode. None of the vector modes will work properly. The motors will vary in speed over their slip range depending upon individual motor loading. The drive will have no ability to "slip compensate". You can minimize this slip speed error by choosing motors with minimum slip.
4. If you put disconnect switches in each drive leg, you would be wise to put pre-action switches on the operator handles. Wire these into an external run enable loop on the drive. This will shut off the drive before the contacts open, avoiding an ugly flash situation if the motor is heavily loaded.
5. You need fuses in each motor lead since the drive ampacity is considerably larger than the motor's. This is often overlooked but, as a general rule, is necessary when you have more than three identical motors on a single drive.

And the individual overload relays for each drive: you may want to stick to bi-metallic type overloads. PWM carrier freqs on the drive output tend to cause spurious tripping of the electronic-type overloads.

You also want to set the carrier frequency to its lowest setting.

Thank you very much for the inputs...