• 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, > U, < f, > 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, installation-specific 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 utilize an internal energy backup.

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  • Undervoltage, overvoltage and frequency monitoring of AC/DC systems, 9.6…150 V (VME421H-D-1), 70…300 V (VME421H-D-2)
  • Without external supply voltage
  • Integrated energy backup
  • Different monitoring functions selectable
    < U, > U, < f, > 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 assignment of basic parameters)
  • LEDs: Power On, Alarm 1, Alarm 2
  • Measured value memory for operating value
  • Continuous self monitoring
  • Internal test/rest 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)
  • Push-wire terminal (two terminals per connection)
  • RoHS-compliant
  • Voltage and frequency monitoring of single-phase machines and electrical installations
  • Earth fault monitoring in medium-voltage systems via voltage transformers
  • Monitoring of battery systems
  • Switching machinery and equipment on and off at a certain voltage level


Optional accessories for LINETRAXX® VME421H

TypeArt No.
Mounting clip for screw fixing (1 piece per device)B98060008

Variants of LINETRAXX® VME421H

TypeNominal system voltage Un*Response valueArt. No.**
VME421H-D-1DC 9,6…150 V / AC 9,6…150 V, 15…46 HzAC/DC 9,6…150 VB73010003
VME421H-D-2DC 70…300 V / AC 70…300 V, 15…460 HzAC/DC 70…300 VB73010004
* absolute values
**(B7… = push-wire terminal / B9… = screw-type terminal)

Downloads for LINETRAXX® VME421H



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