Frequency control relay HHZ

The HHZ control relay monitors frequency variations in 50-60 Hz power networks. Both under- and over-frequencies can be detected by setting two independent limit values. It has two relay outputs, one for each limit value. The switch on the front is set to either 50 or 60 Hz and whether with memory or without memory is preferred. If with memory is selected, the supply voltage must be switched off to restart the relay. The switch position and consequently the relay's function mode is detected when the supply voltage is switched on. If the switch is in an incorrect position when the power is switched on, the component enters error mode. The output remains unaffected and the LED indication flashes to indicate the incorrect position. If the switch position is changed during operation, all LEDs begin to flash but the relay will continue to function normally with the frequency set that was at the most recent power connection. The relay monitors its own operating voltage. The limit value for under-/over-frequency is set with two potentiometers that are scaled based on how much the network frequency may deviate from the set value. There is also a switch that can be used to double the control range. The time delay (Tt), which is adjustable between 0.1 and 10 s. is used to ignore temporary network disturbances. When the time delay is active, either R1 or R2 flashes for a set period. The control relay has a static hysteresis of 0.3 Hz. If the power is switched on with a measured fault, the relay remains unaffected. Green LED (Un) indicates supply voltage OK. Yellow LED (R) indicates active relay output.