The Dold frequency monitor serves the reliable frequency monitoring of alternating currents and the safe monitoring of the phase sequence resp. rotary direction of motors with 3-phase alternating currents. It is used to monitor the output frequency of inverters or the rotor frequency of slip ring motors. An other application area is the monitoring of motors in crane plants. Using the front side display the parameters can be easily and comfortably adapted to the individual application or changed when necessary. With the UH 6937 it is also possible to only monitor the frequency applied or only the rotary direction. Indicator contacts 2 Semiconductor monitoring outputs Measuring motor voltage maximum 690 V Approvals UL