Under-voltage monitoring relay LINETRAXX® VMD420 series

over-voltagefrequencyphase sequence

• Undervoltage, overvoltage and frequency monitoring in 3(N)AC systems 0…500 V • Various monitoring functions selectable U, f • Asymmetry, phase failure and phase sequence monitoring • Adjustable start-up delay, response delay and delay on release The multi-functional VMD420 series voltage relay is designed to monitor the frequency, undervoltage and overvoltage and the voltage between two threshold values 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, installation-specific characteristics, such as device-specific start-up procedures, short-time voltage fluctuations, etc. can be considered. The devices require an external supply voltage. • Undervoltage, overvoltage and frequency monitoring in 3(N)AC systems 0…500 V • Asymmetry, phase failure and phase sequence monitoring • Different monitoring functions selectable  U, f • Start-up delay, response delay, delay on release • Adjustable switching hysteresis • r.m.s. value measurement (AC) • Digital measured value display via multi-functional LC display • Preset function (automatic assignment 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) • N/C or N/O operation and fault memory behaviour selectable • Password protection for device setting • Sealable transparent cover • Two-module enclosure (36 mm) • Indication of the system frequency