Manual MRG3
SEG Electronics GmbH
DOK-TD-MRG3, Rev. D
7
2. Features and Characteristics
Microprocessor technology with watchdog function.
Effective analog low pass filter for suppressing harmonics when measuring frequency, df/dt
and vector surge.
Digital filtering of the measured values by using discrete Fourier analysis to suppress
higher harmonics and d.c. components induced by faults or system operations.
Integrated functions for voltage, frequency, df/dt and vector surge in one device.
Voltage supervision each with two step under-/and overvoltage detection.
Frequency supervision with three step under-/or over frequency (user setting).
Completely independent time settings for voltage and frequency supervision.
User configurable vector surge measurement 1-of-3 or 3-of-3.
Adjustable voltage threshold value for the blocking of frequency-, df/dt or vector surge
measuring.
Independent time over current protection.
Selectable protective functions between:
- definite time over current relay and
- inverse time over current relay,
Selectable inverse time characteristics according to IEC 255-4:
-
Normal Inverse (type A)
-
Very Inverse (type B)
-
Extremely Inverse (type C)
Further characteristics:
-
Long Time Inverse,
-
RI-Inverse
-
RXIDG characteristic
Reset mode selectable for inverse time characteristics.
Definite time element for short circuit fast trip.
Two-step earth fault supervision.
Optionally: sensitive, watt metric directional earth fault detection with measurement of the
residual voltage.
Optionally: supervision of the residual voltage in two steps.
Two parameter sets.
Circuit breaker failure protection with release for subordinate protection.
Functions for the backward blocking.
Display of all measuring values and setting parameters for normal operation as well as
tripping via alphanumerical display and LEDs.
Display of measuring values as primary quantities,
Setting of the switching points for current and voltage measured in per cent.
Voltage fail-safe storage and indication of tripping values in an error memory, 16 times
(voltage fail-safe).
Recording of up to four fault events with time stamp in Comtrade format according to
IEC602555-25.
For the blocking of individual functions via external blocking input, parameters can be set
according to requirement.
Suppression of indication after completed activation (LED flash).
Free assignment of the output relays.
Display of date and time.
Requirements in compliance with VDE 0435, part 303 and IEC 255.
Possibility of serial data exchange via RS485 inter-face possible; alternatively with
RS485 Pro-Open Data Protocol or Modbus Protocol.