G4A01134C

MICROTEMP Thermal Cutoffs: INTRODUCTION Upper Limit Temperature Protection MICROTEMP thermal cutoffs from Therm-O-Disc offer an accurate, reliable solution to the need for upper limit temperature protection. Known as a thermal fuse, thermal link, or TCO, the MICROTEMP thermal cutoff provides protection against overheating by interrupting an electrical circuit when operating temperatures exceed the rated temperature of the cutoff. MICROTEMP Features: One-shot operation cuts off electrical power Current interrupt capacity up to 25 amps 250VAC Low resistance Compact size Operating Principle of the MICROTEMP TCO The active trigger mechanism of the thermal cutoff is an exclusively formulated, electrically nonconductive pellet. Under normal operating temperatures, the solid pellet holds spring-loaded contacts closed. When a predetermined temperature is reached, the pellet melts, allowing the compression spring to relax. The trip spring then slides the contact away from the lead and the circuit is opened (see figures 1 and 2). After a MICROTEMP thermal cutoff opens a circuit, the TCO needs to be replaced. This replacement procedure must include correction of the fault condition before the product is operated again. 1 MICROTEMP G4, G6 & G7 Series TCO Before Operation After Operation CASE AND LEAD CASE AND LEAD ASSEMBLY ASSEMBLY THERMAL PELLET DISCS COMPRESSION SPRING DISCS COMPRESSION SPRING STAR CONTACT TRIP SPRING STAR CONTACT TRIP SPRING CERAMIC CERAMIC BUSHING BUSHING ISOLATED ISOLATED LEAD LEAD EPOXY EPOXY SEAL SEAL Grey area shows Grey area shows opened or current path broken current path Figure 1 MICROTEMP G5 & G8 Series TCO Before Operation After Operation CASE AND LEAD CASE AND LEAD ASSEMBLY THERMAL ASSEMBLY PELLET DISCS COMPRESSION SPRING COMPRESSION DISCS SPRING STAR CONTACT STAR CONTACT TRIP SPRING TRIP SPRING FLOATING CONTACT FLOATING CERAMIC CONTACT BUSHING CERAMIC ISOLATED LEAD BUSHING ISOLATED LEAD EPOXY EPOXY SEAL SEAL Grey area shows opened or Grey area shows broken current path current path Figure 2 2