Thermal Cutoffs Overview Thermal cutoffs are one time temperature activated fuses that permanently open the circuit when a preset temperature is reached. They provide reliable protection against overheating and help prevent component damage and fire risk in a wide range of devices. Key benefits Overheat protection: reliably interrupts current to prevent damage and reduce fire risk. Maintenance : no reset required after actuation; replacement is the only remedy. Broad compatibility: suitable for appliances, power supplies, heating elements, motors, transformers, and battery packs. Flexible options: available in multiple size options and temperature ratings to fit diverse designs. Simple integration: compact cylindrical or disk form factors with standard lead configurations for easy mounting and wiring. What it is and how it works Onetime device: normally closed until the ambient or component temperature reaches the set point, at which the internal element opens the circuit. Fast response: designed to react quickly to rising temperatures to minimize heat exposure to sensitive components. Durable construction: typically enclosed in a metal body with insulated leads to withstand operating environments. Typical specifications to consider Temperature rating: chosen based on the normal operating temperature of the application and the maximum allowable temperature of the protected component. Form factor: cylindrical or disk shapes; various body sizes to fit different panel and wiring layouts. Mounting and leads: axial or radial lead configurations; material often metal alloy with insulated terminations. Reliability: designed for singleuse actuation with stable performance over the expected service life. Compatibility and applications Appliances: protect heating elements, motors, and control circuits in toasters, coffee makers, ovens, and small kitchen appliances. Power supplies and chargers: prevent overheating of transformers, inductors, and DC/DC converters. Heating and motor systems: safeguard windings and impedance components in fans, pumps, and industrial equipment. Battery packs and portable electronics: provide thermal protection in assemblies with heatgenerating components. Size, material, and performance notes Size options range from compact to larger cylindrical bodies; choose based on available space and mounting method. Body materials are typically metal alloys with insulated ends; leads are compatible with standard soldering or crimp connections. Actuation temperature accuracy and tolerance vary by model; select a rating that ensures activation well above normal operation but below component or system limits. How to select and install Choose a temperature rating that is above the maximum normal operating temperature of the protected component and below the allowable limit for safety. Verify lead length, lead material, and mounting method match your wiring and enclosure requirements. Install with secure wiring to avoid vibrationinduced disconnections; ensure the device has adequate heat exposure to reach its trigger temperature when needed. Plan for replacement after actuation; a tripping event indicates the need to inspect the system for root cause before reassembly. Usage scenarios Scenario 1: In a small kitchen appliance, a thermal cutoff is placed in the heating element circuit to shut off power if the element overheats, preventing fire risk and circuit damage. Scenario 2: A linear power supply uses a thermal cutoff on the transformer winding to prevent overheating during peak load conditions. Scenario 3: A cordless power tool or hobby motor assembly includes a thermal cutoff on the motor windings to automatically disconnect if the windings overheat, protecting the device and user. Safety and maintenance Do not bypass or short the cutoff; replacement is required after actuation. Follow manufacturer guidelines for ratings, installation practices, and compliance with applicable safety standards. Inspect periodically for signs of overheating elsewhere in the system, as a cutoff only protects the component it is designed to monitor. Note The information above describes general characteristics and considerations for thermal cutoffs. Refer to the specific model's datasheet for exact temperature ratings, tolerances, form factor, lead configurations, and installation instructions.