Under-voltage monitoring relay LINETRA ® VME420 series

over-voltagefrequency1 NO/NC

Overview
LINETRAXX® VME420 series are multifunction voltage/frequency monitoring relays for undervoltage, overvoltage and frequency supervision in AC and DC systems with a separate external supply. Voltages are measured as r.m.s. values and the current measurement is continuously shown on the multi‑function LC display. The relay stores the measured value that triggered the alarm. Configurable delays and hysteresis permit adaptation to installation-specific start‑up sequences and short transient fluctuations.

Features

• Monitoring of AC/DC systems for undervoltage, overvoltage and frequency in the range 0…300 V
• Selectable monitoring functions: <U, >U, <f, >f (window and limit monitoring)
• Adjustable start‑up delay, response delay and delay on release
• Adjustable switching hysteresis
• r.m.s. value measurement (AC + DC)
• Digital measured‑value display via multi‑functional LC display
• Measured‑value memory storing the triggering value
• Preset function for automatic basic parameter setting
• LED indicators: Power On, Alarm 1, Alarm 2

Functional details
The device requires an external supply voltage. Continuous self‑monitoring and an internal test/reset button increase operational safety. Two independent alarm relays are provided (each one changeover contact), with selectable N/C or N/O operation and selectable fault‑memory behaviour. Device settings can be protected by password and the housing features a sealable transparent cover.

Applications

• Single‑phase voltage and frequency monitoring for machines and electrical installations
• Earth‑fault monitoring in medium‑voltage systems via voltage transformers
• Battery system monitoring
• Automatic switching on/off at defined voltage levels

Variants (excerpt)
Type | Supply voltage U_S* | Nominal system voltage U_n* | Art. No.
VME420‑D‑1 | DC 9.6 V…94 V / AC 16…72 V, 15…460 Hz | AC/DC 0…300 V / 15…460 Hz | B73010001 / B93010001
VME420‑D‑2 | DC 70…300 V / AC 70…300 V, 15…460 Hz | AC/DC 0…300 V / 15…460 Hz | B73010002 / B93010002
* absolute values; ** (B7… = push‑wire terminal / B9… = screw‑type terminal)

Optional accessories

• Mounting clip for screw mounting (one piece per device)
• Mounting frame XM420

Technical specifications

• Monitoring range (nominal system voltage): AC/DC 0…300 V
• Frequency measurement range: 15…460 Hz
• Supply voltage (variants): VME420‑D‑1: DC 9.6…94 V or AC 16…72 V; VME420‑D‑2: DC 70…300 V or AC 70…300 V (15…460 Hz)
• Measured‑value type: r.m.s. (AC + DC)
• Display: Multi‑functional LC display showing current measured value
• Outputs: Two independent alarm relays, each one changeover contact (CO)
• Switching behaviour: Selectable N/C or N/O; selectable fault memory
• Timing: Adjustable start‑up, response and release delays
• Hysteresis: Adjustable switching hysteresis
• Protection: Password protection for device setting; sealable transparent cover
• Mechanical: Two‑module enclosure (36 mm)
• Terminals: Push‑wire or screw‑type depending on variant
• Functions: Measured‑value memory, continuous self‑monitoring, internal test/reset, preset function
• Compliance: RoHS