I have a config as described in the pic. Its a yarn winding machine. Each motor is Single phase 0.25KW. All the 8 runs at the same rpm. there exists a yarn sensor for each.

If the PLC detects a yarn cut from the sensor it should switch off the contactor of that particular motor while inverter running and the user will reset the fault and switches on the contactor again in the running condition itself.

Also the user can switch on or off an individual motor while running.

My question is......Is it possible?

I know that running all the same KW of motors in parallel is possible. But switching in between the inverter running may cause the drive to trip.

If it is possible please suggest me a drive and procedures.

santhosh sundaram

But switching in between the inverter running may cause the drive to trip.

 Normally, to avoid any trips and VFD breakdown, you have to set at Drive output some kind of safety relay, which will not allow to switch the next contactor until pulsation takes place in chain Drive<->Motor.

Msorich

P.S. safety relay example, see attachment.

You cannot open an output contactor on a drive under load without at a minimum tripping it and usually burning up the IGBT's.  When the contactor opens, you will get a voltage spike due to the inductance of the motor.

Use separate drives.

Actually I got some info afterwards. that the motors were 3 phase.

And actually the machine is in running condition without the PLC and HMI and they were running in the same format with the use of relays. one of the machine runs with a Yaskawa drive and they're telling that there is no problem in switching while inverter running.

the main problem is solved and now my part is to automate the same thing with PLC.

But still I dont know how it's configured there? and i'l update once after visiting the machine.

thankyou...

these motors are 0.25kW, 3 phase, the motors will be started direct online from the thread sensor.

The inverter drive needs to be large enough, such that it does not notice the current surge during a start.