Device for monitoring the operating state of an electric motor

In a device for monitoring the operating state of an electric motor, in which a signal transmitter with a temperature sensor is rotationally fixed to the armature, which operates in conjunction with a stationary signal pickup, a signal transmission between signal transmitter and signal pickup is to take place only during a rotational-angle range of the armature, the triggering of a signal by the signal transmitter being suppressed in the event of overtemperature of the armature. As a result, rotational-speed-dependent pulses are triggered by the signal pickup or a subsequent monitoring stage as long as the armature is rotating and the armature temperature does not exceed a permitted limit value. In this manner, both the rotational speed of the armature and its temperature can be monitored by the same means and the motor can thus be reliably protected.