BENDER VMD421H-D-3

The BENDER VMD421H-D-3 is a highly functional voltage and frequency monitoring relay from Bender's LINETRAXX® series, specifically designed for use in 3(N)AC systems. It's a critical component for ensuring the stability and safety of electrical installations by continuously monitoring key grid parameters.

Product Details

The VMD421H-D-3 is a multi-functional voltage monitoring relay. It measures voltages as true RMS values (AC+DC) and continuously displays the current measured value on its LC display. The device also features two separate alarm relays (changeover contacts) and can store the measured value that triggered an alarm. Its compact, two-module enclosure (36 mm width) makes it suitable for integration into various control panels.

Product Parameters (Specifications)

• System Monitored: 3(N)AC systems

• Voltage Measuring Range (True RMS):

• L-N (Line to Neutral): AC 0-288 V

• L-L (Line to Line): AC 0-500 V

• Rated Frequency ($f_n$): 15-460 Hz

• Frequency Display Range: 10-500 Hz

• Monitoring Functions:

• Undervoltage (<U): Adjustable within AC 70-500 V (L-L) / 70-288 V (L-N)

• Overvoltage (>U): Adjustable within AC 70-500 V (L-L) / 70-288 V (L-N)

• Underfrequency (<f): Adjustable within 10-500 Hz

• Overfrequency (>f): Adjustable within 10-500 Hz

• Asymmetry: Adjustable from 5-30 %

• Phase Failure

• Phase Sequence

• Window Discriminator Function (voltage between two thresholds)

• Delay Times (Adjustable):

• Start-up delay (tstart): 0-99 s

• Response delay (ton): 0-99 s

• Delay on release (toff): 0-99 s

• Switching Hysteresis: Adjustable, typically 1-40% for voltage and 0.2-2 Hz for frequency.

• Display: Multi-functional LC display (not illuminated), with LEDs for Power On, Alarm 1, Alarm 2.

• Relay Outputs: 2 changeover contacts (SPDT), configurable for N/C or N/O operation and fault memory (latching) behavior.

• Supply Voltage: Self-supplied by the monitored system (without external supply voltage).

• Integrated Energy Backup: Yes, for continuous monitoring even during brief power interruptions.