The 33 Series instruments offer a wide variety of applications in control, alarm and limit use. Photo conductor sensing eliminates all interference with the indicating meter. These relays incorporate an amplifier input which drives a rugged high torque pivot and jewel or taut-band meter. All voltage rantes are 20,000 ohms/volt (50 µA) and all current ranges have a 50 mV drop. Metal cased "Rugged Seal" construction withstands rigorous environmental conditions. High-gain transistor switching with a "dead band" of no more than 0.5% of full scale. Fail safe circuitry opens output relays in the event of power failure.