Normally closed "make or break" Klixon® contact system, which is operated by a snap action disc, is sensitive to both temperature and current. Precision calibration – temperature calibrated and inspected under controlled conditions for dependable performance. Klixon Phenolic Motor Protectors are equipped with a bimetallic snap acting disc, on which the contacts are mounted, and through which the current flows. If overheating conditions occur, the heating effect of the current flow through the Klixon disc and the influence of motor heat will cause the disc temperature to rise. When the disc reaches the calibrated set point, the Klixon protector automatically opens and shuts down the motor, limiting the winding and shell temperature.