Manual MRG3
SEG Electronics GmbH
DOK-TD-MRG3, Rev. D
43
5.4
Protection parameter “Mains decoupling”
5.4.1
Parameter setting of “Over- and under voltage functions”
The setting procedure is guided by two colored LEDs. During setting of the voltage thresholds the
LEDs U<, U<<, U> and U>> will be flashing up as follows:
U<
U + 1 + <
U<<
U + 2 + <
U>
U + 1 + >
U>>
U + 2 + >
When adjusting the related trip delay, the LEDs will be flashing up as follows:
tU<
U + 1 + < + t>
tU<<
U + 2 + < + t>
tU>
U + 1 + > + t>
tU>>
U + 2 + > + t>
Thresholds of the voltage supervision
During setting of the thresholds U<, U<<, U> and U>> the voltages of the generator rated voltage
are directly displayed in %. The thresholds can be changed by the <+> <-> push buttons and
stored with <ENTER>.
The under voltage supervision (U< and U<<) as well as the overvoltage supervision (U> and U>>)
can be de-activated by setting the threshold to "EXIT".
Tripping delays of the voltage supervision
During setting of the tripping delays t
U<
, t
U<<
, t
U>
and t
U>>
the display shows the value directly in
seconds. The tripping delay is changed via the push buttons <+> and <-> in the range of 0,04 s to
50 s and can be stored with the push button <ENTER>.
When setting the tripping delay to "EXIT" the value is infinite meaning only warning, no tripping.
Note:
When adjusting, the correct positioning of the coding plugs should again be checked (see chapter
3.1.8)
5.4.2 Number of measuring repetitions (T) for frequency functions
In order to avoid false tripping of the unit at short volt-age drops of the system voltage or interfer-
ence volt-ages, the MRG3 works with an adjustable measuring repetition counter. When the instan-
taneous frequency measuring value exceeds (at over frequency) or falls below (at under frequency)
the set reference value, the counter is incremented, otherwise the counter is decremented down to
the minimum value of 0. A trip alarm will only be given when the counter exceeds the value adjust-
ed at T and after expiry of the frequency step’s tripping delay.
The setting range for T is between 2 - 99.
Recommendation for setting:
For short tripping times, e.g. for machine protection or for mains decoupling T should be set in the
range from 2 - 5.
At precision measurements, e.g. exact measurement of the system frequency a setting of T in the
range from 5 - 10 is recommended.