Model ST01 Series

Metric Dimensions are shown in mm (Shown in green)
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These snap action thermal protectors offer exceptional performance in an extremely small package.  Designed as an economical solution, especially for motor, transformer, and lighting applications up to 5 amps, 250 VAC. The round, low-profile design fits perfectly for on-winding protection. Available in a variety of configurations to meet the requirements of many different applications.

A self-hold model is available for applications requiring an additional level of protection.  An internal heat source holds the circuit open until power is disconntected.


  • Snap action design, quick break/quick make switching action.

  • Preset calibration temperature, not adjustable in the field.

  • Brass case provides good thermal conductivity.

  • Case is electrically alive.  Multiple insulation options are available.

  • Standard #22 ga. Silicone rubber insulated lead wires.  Other materials available upon request.

Contact Ratings

Model STO1

  • 5 Amps 250 VAC
  • Maximum operating voltage: 60 VDC, 500 VAC

Calibration Range

  • Available with nominal calibration temperatures from 60ºC to 160ºC
  • Standard calibration tolerance is ± 5ºC


Motors, transformers, lighting, coils, electronics


This model has been evaluated under the components programs by UL and TUV.  Please contact us for further details.

Standard Marking System

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