Frequency monitoring relay LINETRAXX® VMD421H

phase sequencephase lossphase unbalance

Undervoltage, overvoltage and frequency monitoring in 3(N)AC systems 0…500 V Integrated energy backup Asymmetry, phase failure and phase sequence monitoring Adjustable start-up delay, response delay and delay on release Various monitoring functions selectable U, f The multi-functional VMD421 series voltage relay is designed to monitor the frequency, undervoltage and overvoltage and the voltage between two threshold values (window discriminator function) in 3(N)AC systems. The voltages are measured as r.m.s. values. The currently measured value is continuously shown on the LC display. The measured value required to trigger the alarm relay is stored. Due to adjustable response times, installationspecific characteristics, such as device-specific start-up procedures, short-time voltage fluctuations, etc. can be considered. The devices are supplied by the system being monitored and utilise an internal energy backup. Features Undervoltage, overvoltage and frequency monitoring in 3(N)AC systems 70…500/288 V Without external supply voltage Integrated energy backup Asymmetry, phase failure and phase sequence monitoring Various monitoring functions selectable U, f Start-up delay, response delay, delay on release Adjustable switching hysteresis r.m.s. value measurement (AC+DC) Digital measured value display via multi-functional LC display Preset function (automatic setting of basic parameters) LEDs: Power On, Alarm 1, Alarm 2 Measured value memory for operating value Continuous self monitoring Internal test/reset button Two separate alarm relays (one changeover contact each)