interferances

rmonroe

Guest
R
We are experiencing electrical interferences with a Mitsubishi VFD. When the drive runs we get outputs from our PLC going high. Checking from the neutral terminal I see 60VAC TO 90VAC directly off the output module of the PLC. Note; The output modules are relay output at 120 VAC.

This application is a retrofit to an existing piece of production equipment. On this particular system we replaced the combination contactors (Forward/Reverse) with a VFD for a 1 HP motor. This system is a 3 Phase 480 Volt with 120 controls for the PLC devices. We did not us any type of motor shielding or control shielding. I also notice that the motor leads are running in the same conduit as my control I/O wires…could I please get some feedback.

Thanks,
 
insulation rating

No,

The control wires are rated at 300 Volts and the Motor wires are rated at 600 Volts.

Thanks
 
Noise

rmonroe
Do you use an earthing system in this factory.
your motor should be earthed.if you are using 4 wire cable from your VFD to the motor earth it only from one side.
It's also recommended to seperate the motors lead from the control wires specially if you have analoge signals but it seems that it will not be easy to do that in your case .so try the first solution i think that it will work.
Br
 
earth

Hesham,

Thanks for the information, I did earth just one side of the motor and it seems the problem has gone.

best regards,

rmonroe
 
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