Bender VMD421H-D-3 Voltage Monitoring Relay

1. Product Overview

The VMD421H-D-3 monitors undervoltage, overvoltage, and frequency in 3(N)AC systems. It also includes functions for asymmetry (unbalance), phase failure, and phase sequence monitoring. The device is self-powered from the monitored system and features an integrated energy backup to maintain operation during brief power interruptions.

2. Technical Parameters

3. Key Advantages

• Multifunctional Monitoring: Combines voltage, frequency, phase sequence, and asymmetry monitoring in a single compact device.

• Self-Powered: No external auxiliary supply voltage is required, simplifying the installation and reducing wiring.

• Digital Display: The multi-functional LC display provides real-time monitoring of system values and easy parameterization.

• Energy Backup: Integrated energy storage ensures the device can signal a power failure and maintain the alarm state for up to 2.5 seconds.

• Preset Function: Includes an automatic setting function for basic parameters based on the detected nominal system voltage ($U_n$).

4. Product Applications

• Industrial Protection: Monitoring of voltage-sensitive machines and electrical installations.

• Emergency Systems: Monitoring of stand-by and emergency supply systems (e.g., generators).

• Motor Protection: Protecting three-phase motors against phase failure, phase reversal, and asymmetrical loads.

• Transformer Monitoring: Detection of asymmetrical loads to protect distribution transformers.

• Portable Loads: Monitoring supply voltage for mobile or portable equipment.

5. Important Considerations & Precautions

• Installation Safety: Installation must be performed by a qualified electrician. For systems $> 400$ V, strict adherence to local electrical safety standards is mandatory.

• Short-Circuit Protection: It is highly recommended to use 5 A fuses at the sensing inputs (L1, L2, L3, N) for short-circuit protection.

• Neutral (N) Connection: The Neutral connection is only necessary if you intend to monitor Phase-to-Neutral ($L-N$) voltages.

• Configuration Lock: Use the password protection feature to prevent unauthorized changes to the setpoints and delay times.

• Latching Mode: If "Fault Memory" (Latching) is enabled, the device must be manually reset using the "R" button after a fault has been cleared.

Payment: Bank of Chicago, Bank of Singapore

Express cooperation: fedex, DHL, UPS and your express account

Service: Professional Sales provides 24 hours /7 days online service

Related products:

E-mail: alex@fenoux.com

Tel.: +86 13338369201

Skype: +86  13338369201

WhatsApp: +86  13338369201