Dold BA9837.12/020 20-60HZ UH AC230V Safety relay, Part N: 0049773

The frequency relay can be used especially in applications where the rotor frequency of a slip-ring motor must be measured. The rotor frequency is reciprocal proportional to the speed (see diagram rotor frequency at contercurrent braking). This behaviour allows to find speed depending switching values and can be used for start up and contercurrent braking of motors on cranes.