Analog Shaft Speed Sensor with Relay for Hazardous Locations

March 17, 2015

The FB420 Shaft Speed Switch / Shaft Speed Sensor with SPDT Relay works with Electro-Sensors magnetic pulser discs and wraps. It provides a 4-20mA signal directly proportional to the rotational speed of a monitored shaft and has a 4 digit LCD display capable of displaying from 0.000 to 9,999 rpm or from 4 to 20 mA, the display is also used for calibration and troubleshooting. The FB420 has one relay that can be programmed for failsafe over speed alarm or failsafe under speed alarm.

  • 24 VDC powered; terminal blocks for easy wiring
  • Optional EZ-100 mounting bracket available
  • Cast aluminum explosion proof (XP) housing
  • UL Listed Class I, Div I (C, D) Class II, Div I (E, F, G)


Speed Switch on a Bucket Elevator