SEG Electronics GmbH
Manual MRG3
62
DOK-TD-MRG3, Rev. D
6.3 Checking the set values
By repeatedly pressing the push button <SELECT>, all relay set values may be checked. Set value
modification can be done with the push button <+><-> and <ENTER>. (For detailed information
about that, please refer to chapter 4.5 of the description “MR – Digital multifunctional relays”.
Depending on the system conditions and the voltage transformer used, three voltages can be con-
nected to the relay input circuits with either star or delta connection. In case of a star connection
the phase-to-neutral voltage will be applied to the voltage input circuits, while the phase-to-phase
voltages will be connected to the voltage input circuits in case of a delta connection.
The voltage input connection must be set as a parameter, and should correspond with the actual
voltage input connection:
Star connection:
Phase-to-neutral voltages will be measured and evaluated.
Delta connection:
Phase-to-phase voltages will be measured and evaluated.
To assure an efficient operation of the relay, the adjusted rated frequency (f= 50/60 Hz) has to be
concordant with the system frequency (50 or 60 Hz).
6.4 Test with transformer secondary current
(Secondary injection test)
6.4.1 Equipment required to test voltage functions
Voltmeter and frequency meter, class 1 or better,
Auxiliary voltage source supply suitable for the rated auxiliary voltage of the device.
Three-phase alternating voltage source supply with adjustable frequency (voltage:
adjustable from 0 to 2 x UN; frequency: adjustable from 40 - 70 Hz).
Timer to measure the release time (Accuracy class
10 ms),
Switching device and
Test leads and tools.
For testing the vector surge function of the relay, a test circuit which can produce phase angle
change (vector surge) is required to simulate mains failures (please refer to chapter 6.4.8). For
testing the df/dt function of the relay, a special test equipment is required, which can produce a
constant rate of change of frequency.