The multi-function VMD420 series voltage relay is designed to monitor the frequency, undervoltage and overvoltage and the voltage between two threshold values 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. Thanks to the VMD’s adjustable response times, installation-specific characteristics, such as device-specific start-up procedures, short-time voltage fluctuations, etc. can be fully configured. The devices require an external supply voltage.
- Monitoring of voltage-sensitive machines and electrical installations
- Switching on and switching off at a certain voltage level
- Monitoring of stand-by and emergency supply systems
- Supply voltage monitoring of portable loads
- Protection of three-phase motors against phase failure and
- Transformer protection, asymmetrical load can be recognized