VME421H-D-2, voltage relay

Voltage relays

LINETRAXX ® VME421HProduct Description The VME421H series voltage relays monitor frequency, subvoltages, overvoltage and the voltage between two threshold values (window function) in ACand DC systems. The voltages are measured as effective values. The current measured value is permanently displayed on the LC display. The measured value leading to the switching of the alarm relay is stored. Due to adjustable delay times, plant-specific properties can be taken into account: B. device-related start-up phases, short-term voltage changes, etc. The VME421H version removes the supply voltage from the system to be monitored and has an internal energy storage system. Examples of applications • Voltage and frequency monitoring of single-phase machines and systems • Ground-end monitoring via voltage converters in medium-voltage networks • Monitoring of battery systems • Switching on and off systems from a certain voltage function description After the supply voltage is set, the start-up delay "t" starts. During this time, changes in the measured voltage and frequency do not affect the switching state of the alarm relay. The devices have two separately adjustable measuring channels (over- / undervoltage). If the measurement size exceeds the response value ("Alarm 1") or below ("Alarm 2"), the set response delays start "ton1 / 2." After the response delay is over, the alarm relays and the alarm LEDs turn on. The set drop time "toff" starts below or above the measurement size after switching the alarm relay. After the end of "toff" the alarm relays turn back to the initial position. If the error storage is activated, the alarm relays remain in alarm position until the reset key is activated.