Generic KSD301 70°C Normally Closed NC Temperature Control Switch Thermostat - Bakelite, 250V 10A

The KSD301 is a Normally Closed (NC) switch. At room temperature, the contacts are closed, allowing current to flow. When the ambient temperature reaches its 70°C set point, the internal bimetallic disc snaps, physically opening the contacts to break the circuit. It is an automatic reset thermostat; once the temperature cools sufficiently below the set point (typically by 5-10°C), the disc snaps back, closing the contacts again to resume operation.

This thermostat is rated for 10 Amperes at 250 Volts Alternating Current (250V AC / 10A). This rating is typically for resistive loads like heating elements. For inductive loads (motors, transformers), derating is recommended, or use with an appropriate relay, to account for inrush currents and arcing.

Installation is straightforward. The switch has two solder or quick-connect terminals. Wire it in series with the load (e.g., heating element) and the power source. Ensure the metal sensing disc is in good thermal contact with the surface or medium you wish to monitor (e.g., attached to a heater tank wall). The Bakelite body provides insulation, but ensure the mounting environment stays within the material's temperature limits.