Klixon® 3HM Series

Manufacturer: Klixon®

Hermetically sealed motor protector for single-phase on-winding protection

The 3HM hermetic overload protectors are new generation product designed to meet the demands of tomorrow’s compressors. The 3HM family of motor protectors can be applied to air conditioning compressors ranging from 1 to 2½ HP. They may also be used in commercial motors which must function in high-pressure corrosive environments. Its low profile allows ease of installation, while the overall design provides resistance to mechanical shock.

Line Break Operation

Klixon 3HM motor protectors are line break automatic reset controls which are wired in series with the motor windings. These protectors are designed to track winding temperatures and respond to changes in line current, which provides protection against the overload conditions listed below;

  • Running overload
  • High/low voltage locked rotor
  • High voltage light load
  • High discharge temperature
  • Varying of both bimetal and S-wire resistivity creates a current-time characteristic optimized for each specificapplication
  • Unique combination of bimetal disc and resistivity wire guarantees very precise tripping times thus prevents too high motor temperature
  • Protector selection and application testing by Sensata Technologies laboratory with results in extended report at your service


The basic element in the hermetic motor protector series is the Klixon snap-acting disc. An integral series heater allows close control of ON times, and longer cycle rates when stalled rotor condition exists. Glass sealed header is resistant welded to the steel case to provide a hermetic seal. Optional wire leads, sleeve and terminal connector can be provided.

Application Air conditioning compressor from 1 to 2½ HP



  • 3HM
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