Overcurrent Protection in the Bay Unit
191
7SS52 V4 Manual
C53000-G1176-C182-3
TI>>
The parameter
TI>>
(
1203/BU
)
is used to set the trip time delay for tripping of the
high-set current stage (definite-time). The delay time is started when the threshold for
the phase currents is exceeded. This threshold is set with the parameter
I>>
(
1202/
BU
).
MEAS.REPET
The parameter
MEAS.REPET
(
1206/BU
)
is used to select whether a repetition of the
measurement will be performed for the phase currents in the high-set stage.
With setting
YES
the measurement of the phase currents in the high-set stage will be
repeated.
With setting
NO
the measurement of the phase currents in the high-set stage will not
be repeated.
CHARACTER
.
The parameter
CHARACTER.
(
1211/BU
) is used to select the characteristic of the in-
verse-time O/C protection for the phase currents.
This parameter is only displayed if the parameter
CHARAC. PH
(
7812/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 INVERSE
, a characteristic according to IEC 255-3 (type C)
will be used.
I>
I>
(
1212/BU
) and
TI>
(
1213/BU
) are only relevant for the definite time mode
(
CHARAC. PH
=
DEFINITE TIME
(
7812/BU
), Chapter 5.14, page 184). For the set-
ting of the overcurrent stage
I>
the most relevant factor to be considered is the maxi-
mum operating current that can occur. A pick-up caused by overload must be exclud-
ed, since, in this mode, the device operates as fault protection with correspondingly
short tripping times and not as overload protection.
If the
I>
stage is not required, the time
TI>
(
1213/BU
) is set to infinite.
The parameter
I>
(
1212/BU
) is used to set the threshold for the phase currents in the
overcurrent stage.
This parameter is only displayed if the parameter
CHARAC. PH
(
7812/B
U
) is set to
DEFINITE TIME
.
TI>
The parameter
TI>
(
1213/BU
) is used to set the trip time delay for tripping of the over-
current stage. The delay time is started when the threshold for the phase currents is
exceeded. This threshold is set with the parameter
I>
(
1212/BU
).
This parameter is only displayed if the parameter
CHARAC. PH
(
7812/BU
) is set to
DEFINITE TIME
.
Ip
Ip
(
1214/BU
) and
TIp
(
1215/BU
) are only relevant for the inverse-time characteris-
tics (
CHARAC. PH
=
DEFINITE TIME
(
7812/BU
), (Chapter 5.14, page 184). Please
note that in accordance to IEC regulations a safety factor of about 1.1 has been in-
cluded 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
Ip
stage is not needed, the time
TIp
is set to infinite. With setting
0
the protection
trips after the inherent operating time.
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