KSD301 10A 250V Normally Closed Temperature Control Switch – 40C

KSD301 Normally Closed 10A Temperature Control Switch – 40°C is a compact and reliable bimetal thermostat switch designed to open the circuit when the temperature reaches 40°C, making it ideal for thermal protection in appliances, power supplies, battery packs, and heating equipment. Once the temperature drops below its threshold, the switch automatically resets to its closed state.

Key Features:

• Automatic Temperature Control: Opens the circuit at 40°C and resets below that point.
• Normally Closed (NC) Type: Conducts under normal temperature conditions.
• Fast Response Time: Quick and accurate thermal response with snap-action mechanism.
• High Current Handling: Rated for 10A continuous current at 250V AC.
• Reliable and Durable: Long life cycle with bimetal disc design and metal body construction.

Technical Specifications:

• Model: KSD301
• Type: Normally Closed (NC)
• Operating Temperature: 40°C ± 3°C
• Reset Type: Automatic reset
• Rated Voltage: 250V AC
• Rated Current: 10A max
• Contact Resistance: ≤ 50mΩ
• Insulation Resistance: ≥ 100MΩ at 500V DC

Mechanical Specifications:

• Housing Material: Metal casing with bakelite base
• Terminal Type: 2 solder or screw terminals
• Mounting Style: Surface mount with mounting flange

Dimensions:

• Overall Diameter: ~20mm
• Height: ~7mm (excluding terminals)
• Mounting Hole Distance: ~16mm center-to-center
• Terminal Width: ~6.3mm standard tab

Pinout and Wiring:

• Pin 1 & Pin 2: Connected internally when below 40°C
• Disconnection: Opens automatically at 40°C to break the circuit
• Connection: Inline with power supply line for load protection

Datasheet Reference:

• Search online for “KSD301 NC 40°C Temperature Switch Datasheet by SEKI / Generic”

Applications:

• Overheat Protection: Used in heaters, irons, and thermal pads
• Battery Packs: Thermal disconnect in lithium-ion battery protection circuits
• Power Supplies: Cutoff protection for transformers and SMPS units
• 3D Printers: Prevents thermal runaway in heated bed or hotend
• Refrigerators and Coolers: Temperature-triggered relay control

Equivalent Models:

• KSD301 NC 45°C: Same format with higher cut-off temperature
• SEKI ST-22 NC 40°C: Similar snap-action thermostat with equivalent specs
• Thermodisc 36T Series: US-made equivalent bimetal thermal switch
• Uchiya UX Series: High-reliability thermal protectors with NC configuration

Package Includes:

• 1 x KSD301 40°C Normally Closed Temperature Control Switch (10A 250V AC)