Generic KSD9700/BK05-BB1D 5A 250V Metallic Shell Temperature Control Switch (140C Normally Open)

A 'Normally Open' (NO) configuration means the electrical contacts are open (circuit broken) at room temperature. When the surrounding temperature rises to the calibrated trip point (140°C), the internal bimetallic disc snaps and opens the contacts further, maintaining the open state. The circuit remains broken until the temperature cools below the reset point, at which point the contacts close again to restore power.

Wire the switch in series with the load (e.g., a heating element or motor) and the power source. The two lead wires are not polarized, so either wire can connect to the line or load side. Ensure the metallic sensing head is in good thermal contact with the component or area you need to monitor. The switch will automatically interrupt the current when its sensed location reaches 140°C.

Yes, the switch is rated for up to 250V AC or DC. It can handle a continuous current of 5 Amperes under either voltage type. Ensure your application's maximum voltage and current do not exceed these ratings to maintain safe and reliable operation over the switch's lifetime.

The switch features automatic reset. After tripping open at 140°C, the internal bimetallic disc will begin to return to its original shape as it cools. The contacts will typically close again (resetting) when the temperature drops approximately 10-20°C below the trip point, though the exact differential can vary. This allows for automatic restoration of circuit function once the over-temperature condition is resolved.