lämpökatkaisin

lämpökatkaisin is a Finnish term that translates literally to “temperature breaker” or more commonly to “thermal cut‑off” or “thermal switch.” It refers to a safety device that interrupts the flow of electrical power when a device or circuit reaches a preset temperature threshold. Unlike general thermostats that maintain a set temperature, a lämpökatkaisin is intended to prevent overheating and protect equipment, wiring, or life from potential fire hazards.

The core of a lämpökatkaisin is a bimetallic strip or a semiconductor element that changes its resistance with temperature. As temperature increases, the strip bends or the resistance rises, forcing an internal relay to open the circuit. In some designs the device uses a fusible link that melts at a set temperature, providing a single‑use safety cutoff. Lämpökatkaisijat are widely used in electric furnaces, heat pumps, air‑conditioning units, electric heaters, and electrical distribution boards.

There are several variants depending on rated current, voltage, and speed of response. Low‑current models (up to 6 A) are used for small appliances and automotive electronics, while high‑current models (over 100 A) protect large industrial furnaces and power supplies. Many modern safety switches incorporate digital monitoring that records the highest temperature reached and can communicate this information via CAN bus or Ethernet to supervisory control systems.

Installation guidelines recommend mounting the device at the point of heat generation, ensuring the sensor has direct contact with the hottest component. The bypass circuit should be sized to carry the full load current, and metal‑clad wiring is preferred to reduce extraneous heat conduction. Correct selection and routine testing of lämpökatkaisuja are essential for compliance with electrical safety codes and for preventing fire‑related accidents.