Littelfuse introduces TCMOV and SMOV Series Thermally Protected Varistors with micro-switch indicators to help manufacturers meet the requirements specified in UL1449 (3rd edition) for Type 1 or Type 2 Surge Protection Device (SPDs) applications.
TCMOV Series are 34mm2-format varistors that combine high maximum surge capability (50kA) with an integrated thermally active element. In the event of overheating due to abnormal overvoltage, the TCMOV Varistor safely disconnects from the circuit. A built-in micro-switch triggered by a mechanical slide indicates when a circuit is completely isolated from the primary circuit.
SMOV Series varistors offer high peak surge current handling and energy absorption capabilities with an operating voltage range compatible with common AC line voltage (115VAC to 750VAC). Designed to safely disconnect from the circuit in a sustained over-voltage, intermediate current condition, a separate micro-switch indicates when the MOV has been disconnected from the circuit. This separate switch isolates the monitoring circuitry from the primary circuit to ensure indicator circuit safety and simplify the user’s circuit design.