The VME421H-D-1 is a multifunctional voltage and frequency monitoring relay from Bender, part of the LINETRAXX® series. It is designed for AC and DC systems to monitor undervoltage, overvoltage, underfrequency, overfrequency, and window discriminator functions. Voltage measurement uses the true RMS (AC+DC) method to ensure accuracy even in harmonic‑rich industrial environments.
The device requires no external auxiliary supply; its operating power is taken internally from the monitored system voltage. An integrated backup power supply ensures continued monitoring even during a complete power failure of the monitored system.
Technical Specifications
· Rated system voltage (Uₙ): DC/AC 9.6…150 V, 15…460 Hz
· Monitoring functions: Undervoltage, overvoltage, underfrequency, overfrequency, window discriminator
· Alarm relays: Two independent changeover contacts (K1, K2), AC 250 V / 6 A
· Measurement accuracy: Voltage ±1.5%, frequency ±0.2%
· Response time: Voltage ≤ 140 ms; frequency ≤ 335 ms
· Display: Multi‑function LCD display with backlight
· LED indicators: Power On (green), Alarm 1 (yellow), Alarm 2 (yellow)
· Adjustable time delays: Start‑up delay, response delay, release delay
· Operating temperature: –25 °C … +55 °C
· Mounting: DIN rail, width 36 mm (2 standard modules)
· Connection types: Push‑wire terminals (order no. B73010003) or screw terminals (order no. B93010003)
· Standards compliance: IEC 60664‑1, IEC 60664‑3, IEC 61010‑1
Key Features
· No external supply required – Powered directly by the monitored system voltage
· Integrated backup power – Internal energy storage ensures continued monitoring even during supply failure
· True RMS measurement (AC+DC) – Accurate voltage measurement with harmonic distortion and non‑sinusoidal waveforms
· Multifunctional monitoring – Undervoltage, overvoltage, underfrequency, overfrequency, window discriminator
· Two independent alarm relays – Configurable for different alarm conditions with N.O./N.C. operation
· Adjustable time delays – Start‑up delay, response delay, release delay to prevent nuisance tripping
· Adjustable hysteresis – Prevents relay chatter due to voltage fluctuations
· Preset function – Automatically assigns basic parameters on first power‑on, simplifying commissioning
· Digital measured value display – Continuous real‑time display on LC display
· Measured value memory – Stores the value that triggered the alarm relay for fault diagnosis
· Continuous self‑monitoring – Automatic self‑test ensures operational reliability
· Password protection – Sealable transparent cover prevents unauthorised parameter changes
Typical Applications
· 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 at specific voltage thresholds
· Voltage protection for voltage‑sensitive electrical equipment
· Monitoring of emergency and standby generators
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