SEKI CK Series Thermal Protection Switches

SEKI’s CK series thermal protectors can protect electric motors, transformers and solenoids against over-heating.  The snap-action bimetal blade is electrically conductive and so responds both to over-temperature and over-current conditions.  The SEKI CK thermal cut-out can be calibrated from 60℃ to 160℃ in 5K steps with a temperature tolerance of ±5K.

Various lead-wire options are available as well as axial opposed terminals for in-line protection applications.  The metal case is live and so various insulating sleeves or plastic cases are available to electrically isolate the housing from the protected appliance.

For vacuum impregnation applications such as HID ballasts, the CK has a patented double-coating to help prevent the ingress of varnish.  Call us to discuss any specific thermal protector requirements.


  • AC electric motors
  • Transformers and solenoids
  • Fluorescent and HID ballasts
  • Electric heater pads
  • Vacuum cleaner motors
  • Automotive accessory motors


  • Snap Action
  • Patented Double Coating Technology To Prevent Varnish Penetration
  • Wide Selection of Leads and Insulating Sleeves
  • Contact Rating: 8A/250V AC (6,000 cycles)
  • Temperature Setting Range: 60℃ to 160℃
  • Safety Certification: UL/cUL, TUV, CQC,  KC
Cost effective over temperautre protection - electric motors