Struthers-Dunn M60AAA-120A Power Relay

The Struthers-Dunn M60AAA-120A Mercury-Displacement Power Relay is a three-pole, AAA (3 normally open) mercury-displacement switch with a 120 VAC coil, rated for 60 A loads on 120/240 VAC resistive applications and up to 60 A at 28 VDC. It supports AC and DC coils, with nominal coil power of 7–28 VA for AC operation or 3–9 W for DC operation, and accepts tolerances of 85–110% of nominal for AC and 80–110% for DC, with a 10% dropout voltage. Operate and release times are typically 50 ms and 80 ms, respectively, enabling rapid switching of high-current circuits. The device features a very low initial contact resistance (50 milliohms max at 6 VDC) and a dielectric strength of 2650 Vrms across open contacts and between insulated points, with insulation resistance of 1000 megohms at 500 VAC. Environmental and endurance specs include an operating temperature range of -34 to 74 °C and storage from -40 to 105 °C, plus electrical life of about 250,000 cycles and mechanical life around 5,000,000 cycles.