SEKI HB Series Thermal Switch

SEKI HB 1/2″disc bimetal thermal cut-outs (also known as thermal switches) offer users a compact temperature control solution at competitive pricing.  These parts use a 1/2″diameter bimetal disc (hence the name!) that inverts from concave to convex as it reaches its set-point.  This action then opens a set of electrical contacts and opens the circuit.

The SEKI HB disc cut-outs are available as automatic reset devices (with a wide temperature differential) or as manual reset thermal cut-outs which have a push-to-reset button.  They can also be configured to be single-shot thermal fuses which cannot be reset in ambients even as low as -35°C.

Various terminal types (solder tabs, 4.8mm and 6.3mm push-on tabs) as well as numerous flanges and mounting options make the HB series a flexible range of thermal switches.  The HBs can also be fitted with normally-open (close-on-rise) contacts to operate as a warning device or to switch on a cooling fan.


  • Automatic Coffeemakers
  • Water Heaters
  • Sandwich Toasters
  • Dishwashers
  • Tumble Dryers
  • Electric Heaters
  • Microwave Ovens


  • Snap-Action, Auto-Reset or Manual-Reset Contacts
  • Normally-Closed (N/C) or Normally-Open (N/O)
  • Contact Rating: 15A/250V AC (100,000 cycles)
  • Temperature Setting Range: -20℃ to 180℃
  • Safety Certification: UL/cUL, TUV, CQC, KC
  • SOD (Single Operation Device) Fuse Option
Cost effective range 1/2