Photoelectric & noise

[theripley]

Can noise (electrical noise) affects a photoelectric sensor?

We have encountered a case wherein the signal "chatters", but when wire was replaced with a shielded wire (with wire shield properly grounded), the signal does not "chatter" anymore.

Can someone help me figure this out?

 

[adisharr]

The most common cause of sensor noise I've run into is when the sensor wire is run in close proximity to a noisy source (inverter, high voltage, etc..)

Inverters are especially noisy. Many times the motor cabling isn't shielded.

 

[Ken Roach]

Definitely.

I once had to replace all of the 2-wire inductive proximity sensors on a machine with 3-wire sensors because the 2-wire would "chatter" when the nearby VFDs turned on.

 

[theripley]

I see. The sensor wire is in proximity to the motor wires from VFD, I now know. Thank you.

Aside from using shielded wire, is there any other option? Shielded wires are quiet expensive.

 

[iant]

either use electrical isolation by distance.
or a 'Faraday Cage' / steel conduit.
(this is the effect of shielding)
what you are looking at is an induced voltage.