Overcurrent Protection in the Bay Unit
193
7SS52 V4 Manual
C53000-G1176-C182-3
MEAS.REPET The parameter MEAS.REPET (1506/BU) is used to select whether a repetition of the
measurement will be performed for the earth current in the high-set stage.
With setting YES the measurement of the earth current in the high-set current stage
will be repeated.
With setting NO the measurement of the earth current in the high-set current stage will
not be repeated.
CHARACTER. The parameter CHARACTER. (1511/BU) is used to select the characteristic of the in-
verse-time O/C protection for the earth current.
This parameter is only displayed if the parameter CHARAC. E
(7815/BU) is set to IN-
VERSE TIME.
With setting NORMAL INVERSE, a characteristic according to IEC 255-3 (type A) will
be used.
With setting VERY INVERSE, a characteristic according to IEC 255-3 (type B) will be
used.
With setting EXTREMELY INVERS, a characteristic according to IEC 255-3 (type C)
will be used.
IE> For earth faults the pickup values and delay times can be set individually. This allows
to use a different grading with shorter delays for earth faults. IE> (1512/BU) and
TIE> (1513/BU) are only relevant for the definite-time mode (CHARAC. E = DEFI-
NITE TIME (7815/BU), Chapter 5.14, page 184). For setting the overcurrent stage
IE> the most relevant factor to be considered is the lowest earth fault current that can
occur.
If the IE> stage for earth faults is not to be active at all, the delay time TIE> (1513/
BU) can be set to infinite.
The parameter IE> (1512/BU) is used to the threshold for the earth current in the
overcurrent stage.
This parameter is only displayed if the parameter CHARAC. E (7815/BU
) is set to DEF-
INITE TIME.
TIE> The parameter TIE> (1513/BU) is used to set the trip time delay for tripping of the
overcurrent stage. The delay time is started when the threshold for the earth current
is exceeded. This threshold is set with the parameter IE> (1512/BU).
This parameter is only displayed if the parameter CHARAC. E (7815/BU
) is set to DEF-
INITE TIME.
IEp IEp (1514/BU) and TIEp (1515/BU) are only relevant for the inverse-time characteris-
tics (CHARAC. E = DEFINITE TIME (7815/BU), Chapter 5.14, page 184). This al-
lows to use a different grading with shorter delays for earth faults. Please note that in
accordance to IEC regulations a safety factor of about 1.1 has been included between
the pick-up value and the setting value. This means that a pickup will only occur if a
current of about 1.1 times of the setting value is present. If the IEp stage for earth is
not to be active at all, the delay time TIEp can be set to
infinite.
If the I
Ep
stage is not needed at all, the time TIEp is set to infinite. With setting 0 the
protection trips after the inherent operating time.
The parameter IEp (1514/BU) is used to set the threshold for the earth current in the
overcurrent stage of the inverse-time O/C protection.
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