LINETRAXX® VMD258 undervoltage/overvoltage relay for monitoring three-phase AC systems up to 690 V in pure analogue technique.
The voltage relays VMD258 of Bender monitor three-phase AC systems for undervoltage and overvoltage (window function). Neutral conductor connection is not required, therefore it is suitable for 3AC systems up to 690 V.
The voltage to supply the electronics is taken from the system to be monitored. The supply of the electronics, the relays and the connection for the external energy storage device are isolated from the system by means of double isolation. The additional energy storage device ES258 provides a stored energy time of at least 5 s in the event of power system failure. Special input transformers attenuate interferences from the system.
The response values for undervoltage and overvoltage as well as the response delays are continuously adjustable.
The LINETRAXX® VMD258 series complies with the requirements of the device standards: DIN EN 60255-1 VDE 0435-300 und DIN EN 60255-127 VDE 0435-3127.
The pure analogue design of the device series (without microcontrollers) is a requirement resulting from risk analyses of safety-critical areas.
The analogue technique of VMD258 is primarily used by energy suppliers, e.g. in power plant technology or in substations and replaces the SUR35x series.