Under-voltage monitoring relay LINETRAXX® VMD423/VMD423H
over-voltagefrequencyphase sequence

under-voltage monitoring relay
under-voltage monitoring relay
under-voltage monitoring relay
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Measured/monitored value
under-voltage, over-voltage, frequency, phase sequence, phase loss, phase unbalance
Contact configuration
1 NO, 1 NC
AC, three-phase
Other characteristics
multifunction, digital


The LINETRAXX VMD423 and VMD423H voltage relay models are designed for AC systems. Frequency and voltage are monitored in accordance with DIN-V-VDE-V 0126-1-1 for the purpose of feeding power into a low voltage public grid from private generation systems greater than 30kW. Examples include wind power generators, photovoltaic systems, CHPs, etc. The output frequencies and voltages are measured via 100V transmitters at the feeding point of a medium voltage grid. When the limit values are attained, an alarm relay is triggered within ≤80ms. These relay models can be adapted to the requirements of individual electricity supply companies. Overvoltage is monitored by average determination of the previous ten-minute measuring intervals. Additional features include rms value measurement for AC+DC, start-up delay, delay on release, adjustable switching hysteresis, etc.


*Prices are pre-tax. They exclude delivery charges and customs duties and do not include additional charges for installation or activation options. Prices are indicative only and may vary by country, with changes to the cost of raw materials and exchange rates.