Speed Monitoring

Siemens - Relays Speed Monitoring

The speed monitoring relay monitors a motor for exceedance of the upper and lower limit via a sensor attached to the motor, which supplies one impulse per rotation. A speed signal edge is evaluated to also ensure the reliable detection of motors and systems in idle states. Thanks to a scaling factor, up to ten sensors can be placed per rotation to accelerate the measuring with extremely slowly rotating motors while still measuring the present speed correctly.


  • Monitoring for belt breakage or slippage

  • Load shedding

  • Standstill monitoring (not for personal protection)

  • Transport item monitoring for completeness

Advantages at a glance

  • Global applicability thanks to wide-voltage range of 24 – 240 V AC

  • Variably settable for upper/lower limit exceedance or window monitoring

  • Freely parameterizable delay times and reset behavior

  • Permanent display of actual value or fault type

  • Use of up to 10 sensors per rotation with extremely slowly rotating motors

  • Two- or three-conductor sensors connectable

  • Sensors with mechanical switching or electronic output connectable

  • Integrated sensor power supply