Hi there,

I'm looking for a solution in how to fix a problem I have a clothes extractor. I want to convert contactor control to VFD. I need to control the direction and speed of the extractor. The machine does have a mechanical timer that activate three contactors in the the right sequence, FWR 300 rmps, Distribution 600 rpms, FWR-SPIN 4000 rmps and REV 300 rpm.

How could I use the four signals coming from the mechanical timer (220V) to the contactors to control a VFD.

Power Source 220V AC 1PH
Motor is 220V AC 3PH 1.5 Kw

Thoughts and suggestions are welcome.

Thanks for your help.

 

Some VFDs have Digital Inputs allowing to program up to 16 motor's speeds - see VFD from Delta or Fuji Electric for example.

 

> The machine does have a mechanical timer that activate three contactors in the the right sequence, FWR 300 rmps,
> Distribution 600 rpms, FWR-SPIN 4000 rmps and REV 300 rpm.

> Power Source 220V AC 1PH
> Motor is 220V AC 3PH 1.5 Kw

You need 3 different speed setpoints 300, 600 and 4000. this could be a simple series of resistors or resistors and trimpots.

Most VFDs put out a reference Voltage e.g. 5 or 10 Volts.
OR
Some VFDs have several digital inputs that can be configured to operate the VFD at a fixed speed when turned on.

The tricky part might be finding a VFD that will operate off single phase 220 and output 3 phase 220 although usually they can with some de-rating.

Assuming a 2 pole motor at 4000 RPM you will need 67 hz, that shouldn't be a problem.

Q, how do you get 4000 RPM at the moment with just contactors, are you using a brushed motor?

Talk to your VFD suppliers