KSD9700/BK05-BB1D Metallic Shell Temperature Control Switch - 85°C Normally Open, 5A 250V

The KSD9700/BK05-BB1D is a Normally Open (NO) switch. This means its contacts are open at room temperature and do not conduct current. When the temperature rises to its 85°C setpoint, the internal bimetallic disc snaps to close the contacts, completing the circuit. It is typically used in a safety cutoff configuration where the switch is placed in series with the load, and a rising temperature triggers an alarm or shutdown by closing the circuit.

Yes, this switch is rated for 250V AC/DC and can handle up to 5A of resistive current on either type of supply. Ensure your application's voltage and current do not exceed these ratings. The snap-action mechanism is designed to break both AC and DC arcs effectively, though inductive loads (like motors) may require additional arc suppression for optimal contact life.

Install the switch with its metallic shell in direct thermal contact with the component or surface you wish to monitor (e.g., motor housing, heatsink). Secure it using thermal adhesive or a mounting clip. Connect the two pre-attached 7cm lead wires in series with the power line of the device you want to protect. Polarity does not matter for this SPST switch. The switch will automatically reset once the temperature drops below its reset point (typically 10-15°C below the trip temperature).

Standard bimetallic thermal switches like the KSD9700 series typically have a manufacturing tolerance of ±5°C around the stated setpoint. Therefore, the actual trip temperature for this 85°C model can range from approximately 80°C to 90°C. For critical applications requiring tighter tolerance, a calibrated thermal sensor with electronic control is recommended.