The measuring relay simultaneously monitors up to nine quantities of a single- or three-phase network - voltage, voltage asymmetry, current, power factor, active, reactive and apparent power, frequency and phase sequence - and handles parameterisation, reading of measurements and diagnostics through a galvanically isolated Modbus RTU interface. Measured values and error messages reach the controller or supervisory system this way, which turns the relay into a network measuring point without a separate meter. Each function has a minimum, maximum or window threshold, hysteresis, response delay and start-up delay; the error memory keeps the cause of the trip.
DOLD lists the applications: simple monitoring of electrical quantities in complex and extensive plants, voltage-dependent switching, motor protection on phase failure, transformer protection on asymmetric load, frequency monitoring on inverter outputs. Two relay outputs allow warning and trip to be separated, and the function of each output (energised or de-energised on trip) is set from the bus.
For railways we propose it where the supply state of a trackside cabinet, substation or technical room has to be visible in the supervisory system: Modbus RTU carries measurements and alarms to the site controller, while the contacts perform the local trip.
Parameters (UG 9400.12PM, from the datasheet):
