KSD9700/BK05-BB1D Metallic Shell Temperature Control Switch - 125°C NC, 5A 250V

The KSD9700/BK05-BB1D is a Normally Closed (NC) switch. Its contacts are closed under normal operating temperatures. When the temperature at the sensing head reaches its calibrated setpoint of 125°C, the internal bimetal disc snaps and mechanically opens the contacts, breaking the circuit to provide over-temperature protection.

This thermal switch is rated for a continuous current of 5 Amperes at a maximum voltage of 250 Volts, which can be either AC or DC. It is crucial not to exceed these ratings to ensure reliable operation and prevent contact welding or failure under load.

Install the switch by firmly attaching its metallic shell to the component or surface you need to monitor (e.g., a motor housing or heatsink) using thermal adhesive or a clamp to ensure good thermal contact. Connect the two lead wires in series with the load (e.g., a motor or heating element) on the live side of the circuit. The switch will automatically open at 125°C and reset once the temperature cools sufficiently.

Yes, this is an automatic reset thermostat. Once the temperature at the sensing head drops below the reset temperature (typically several degrees below the 125°C setpoint), the bimetal disc will snap back to its original position, closing the contacts again and restoring power to the circuit without manual intervention.