So spent a morning at a customer and ran into an issue that had me a little baffled, and at this point my assumption (without pulling out an extra bit of test gear like an oscilloscope) is that the 24vdc powering their prox is combining with other issues like induced voltage or insulation leak to cause part of their problem.
anyway. the sensor is a balluff BES 326 series pnp 3 wire. there are two sensors (not identical, don't know what the other is either, too deep) and they share 24v and 0v wirenutted together.
then the offending sensor will stay illuminated and show anywhere from 1-2.4vdc on the signal out wire (black/N.O.) and fluctate with other equipment action. The actual sensor itself and wiring being held outside the cabinet is not running next to any other source of power from the wire nuts to the sensor held in hand. but yet the sensor stays lit even without an object in front of it..... Triggering the prox by putting it in front of metal gives us a 23v output and the light stays brightly lit of course.
The questions remains, how would a 3-wire prox sensor light up and show output voltage without anything connected to its output wire, just power to the sensor and thats it. they also attempted to try a couple different sensors, all balluff, that react the same as well.
The final fix for them was to just put an interposing relay in between and eat the little bit of voltage in the line through the coil so it won't keep specific drive inputs on. But this doesn't help explain the weird electrical event going on.
anyway. the sensor is a balluff BES 326 series pnp 3 wire. there are two sensors (not identical, don't know what the other is either, too deep) and they share 24v and 0v wirenutted together.
then the offending sensor will stay illuminated and show anywhere from 1-2.4vdc on the signal out wire (black/N.O.) and fluctate with other equipment action. The actual sensor itself and wiring being held outside the cabinet is not running next to any other source of power from the wire nuts to the sensor held in hand. but yet the sensor stays lit even without an object in front of it..... Triggering the prox by putting it in front of metal gives us a 23v output and the light stays brightly lit of course.
The questions remains, how would a 3-wire prox sensor light up and show output voltage without anything connected to its output wire, just power to the sensor and thats it. they also attempted to try a couple different sensors, all balluff, that react the same as well.
The final fix for them was to just put an interposing relay in between and eat the little bit of voltage in the line through the coil so it won't keep specific drive inputs on. But this doesn't help explain the weird electrical event going on.