Otek Model 900 Current Loop Controller
Model 900 current loop controller requires no external power to operate. High and low setpoints measure and compare the current loop to a setpoint, turning on or off the isolated solid state relays and alarms LEDs. The unit can be used as a standalone in any 4-20 mA loop or mounted in series with other devices. It's available as a loop-powered (4-20 mA) transmitter or controller.