KSD9700/BK05-BB1D Metallic Shell Temperature Control Switch - 100°C Normally Open, 5A 250V

The KSD9700/BK05-BB1D is a temperature-activated safety switch. It is wired in series with your load. Under normal operating temperatures (below 100°C), its Normally Open contacts are closed, allowing current to flow. When the temperature at the switch's metallic shell reaches its 100°C setpoint, the internal bimetallic disc snaps, opening the contacts and cutting power to the load, thereby preventing overheating damage.

Yes, this thermal switch is rated for 250V and 5A, which applies to both AC and DC circuits. Ensure your application's voltage does not exceed 250V and the current (especially inrush or inductive loads) does not surpass the 5A resistive rating for reliable operation and contact longevity.

Installation requires physically mounting the metallic shell of the switch to the component or surface you wish to monitor (e.g., a motor housing or heatsink) using thermal adhesive or a clamp to ensure good thermal contact. Electrically, connect its two lead wires in series with the live/hot wire of the load you want to protect. The switch acts as an automatic, resettable fuse that opens on over-temperature.

"Normally Open" (NO) means the switch's internal contacts are open (no continuity) when the device is cold and below its setpoint temperature. To use it, you wire it so that when the temperature is safe, an external mechanism (like a relay or controller) closes the circuit. However, for the common KSD-type protector, 'NO' typically describes its state at room temperature; it is supplied closed and opens at the setpoint. For this model, it is a series safety cut-off that is closed during normal operation and opens upon fault (overtemperature). Confirm the specific logic for your application.