The name of motor protection sensors are often determined by their usage. Therefore, cable thermometers of the series M-OK/xx resp. M-OK/KH are known as coil/winding sensors, because they are used, as well as PTCs, inside of the coils and windings of electrical machines. Screw-in thermometers type EM24 are named bearing thermometers, because they are used to monitor the bearing temperature of big motors and generators. The third group are the slot resistance thermometers (SRT). They measure, as bifilar wire wrapped sensors, an average temperature inside the stator slots of electrical machines. The average temperature corresponds with the temperature sensitive length of the thermometer. SRT with thin film sensors only measure a spot temperature inside of the slot.
