Using proximity switches for speed control – we have seen customers use these techniques to understand and monitor speed of their equipment
A proximity switch can be used to measure the speed of a conveyor belt, pump, etc by putting a metal disc on a rotating shaft that runs at the speed you wish to measure. The metal disc should have holes punched in it large enough to allow the proximity switch to switch on and off. A PLC will then take this input (may have to use a high speed input card if the pulses from the proximity switch come too fast) and then you can use it to monitor the equipment speed. If you take pulses/minute and make it proportional to feet per minute – you then have speed control. In this case you would have a counter measure pulses triggered by a timer counting every 60 seconds. The PLC can do the calculation for you equating pulses per revolution to whatever is the equivalent feet per minute. An economical and good proximity switch for this application would be Eaton’s Global Series of proximity switches (Eaton # E57-12GE10-CDB/ Newark #63P9108 for 10-30 VDC operating voltage). A good high speed proximity switch for this application is Eaton’s iProx (Eaton #E59-M18C118C02-A2 / NEWARK# 47K644 FOR 20-132 VAC or Eaton #E59-M12A105D01-D1/ Newark # 47K7601 for 6-48 VDC). The optional software will allow you to program an output for speed control very easily within the software
Motion Position Detection
A tubular E57 proximity sensor is used to detect the presence of set screws on a shaft hub providing a control device with signals for speed regulation or detection of rotation.
Prox Switches are available with a micro connector or a 2 meter (6.5 foot) cable. Eaton offers the Global Series, Global Plus and iProx proximity switches through Newark which you many want to check out.