transformer noise


Thread Starter

Gantt Robert

Hello list members:

We are currently installing a PLC-based monitoring and control system (with analog and digital I/O and T/C inputs, mounted on a metallic enclosure). Because of space considerations, we were forced to mount the enclosure just 2 feet above a large transformer that powers a 50 HP DC drive and a few small DC and AC drives.

Power cables to/from the transformer and control cabling are pretty much apart, as power cables run at or below ground level while control wiring extend upward through metallic conduit. All analog I/O runs through shielded cable, grounded at one end, with separate raceways for low-level and high-level lines, etc. all the "normal" precautions.

However, I'm concerned about the closeness of the transformer with the control cabinet. Has anybody had any experience (positive or negative) with control
cabinets near large transformers? Could I expect trouble? At least there are no servomotors or large AC drives (which I know cause the most trouble if
their related harmonics and EMI are not properly taken care of)

Thanks in advance for any comment.

Should Give No Problem if the PLC cabinet properly Earthed.
If Noise is seen on analogue inputs then could try using 4-20mA .