The monitoring of rotation speed or rotating movements is necessary in many applications to ensure the proper operation of the plant. Our rotation- and zero speed monitors operate according to different operating principles: 1. Monitoring of pulses of a transducer via a current transfomer, 2.Frequency measurement of the phase current Our devices feature, depending on the type, a wide variety of functions. For a further evaluation in a higher-level control, the results are i.e. outputted as easy relay contact (over-/ underspeed) or as analog output signal resolved to the set rotation speed range.