Safe monitors for speed, direction of rotation, standstill and position

Our safety relays are used in modern plants and mechanical engineering to protect people and machines. They can be flexibly used as speed, direction, standstill and position monitors.

Standards such as DIN 61508 and EN ISO 13849 set increased demands on the safety criteria. Therefore, the speed monitors of our DS series are SIL3/PLe and SIL2/PLd certified. As a result, they guarantee the highest level of reliability and safety by monitoring speed, movements and positioning. In addition, the safety relays with analog output provide additional feedback that can be used for control purposes.

All motrona safety relays and speed monitors are designed for an easy installation in the control cabinet.

DS series

Safety Speed Monitors

Safety devices for speed, direction of rotation and standstill with SIL3/PLe and SIL2/PLd certification.

DZ series

Speed Monitors

Monitoring of overspeed, underspeed, direction of rotation or standstill.


Position Monitors

Combined monitors for speed, position, slip and shaft breakage.

The task of a speed monitor is, as the name says, the monitoring of overspeed, underspeed, direction of rotation or standstill. The speed monitors from motrona are used when there are high safety criteria for the safety and reliability of a system. In particular when the highest protection requirements for man and machine are needed, the safety relays of the DS series, with the double certificate according to DIN 61508 and ISO 13849, offer a high level of safety.

The safety relay is able to measure the speed and compare it to preset limits. Thus, the speed monitor can detect a lower or over frequency and stop the machine immediately. The safe standstill of systems can also be monitored, e.g. to protect the personnel and machine from undesired start of the drives. In conclusion, a speed monitor is used to monitor and analyse speeds to take measures for preventing risks and damage.

Typical applications in which a speed monitor is used are the following:

  • centrifuges
  • cranes (gantry crane, overhead crane, process crane, single / double girder overhead traveling crane, retrofit)
  • fans
  • wind turbines
  • high rack storage systems
  • transport systems and conveyor systems
  • saws/ woodworking machine
  • test benches
  • balancing machines, grinding machines, agitators, filling machines and many more.

Due to the increasing degree of automation and the advancement of technology, aspects such as safety and risk reduction are getting more important. Therefore, the application fields and demand of safety relays are increasing.