Functions
184
7SS52 V4 Manual
C53000-G1176-C182-3
5.14
Scope of Protective Functions in the Bay Unit
5.14.1 Functional Description
An optional overcurrent protection is provided as a backup protection in the bay units.
This protection works independently of the busbar protection function and remains ac-
tive even if the link to the central unit is interrupted or if the bay unit is set with the pa-
rameter
XX12/CU
) to bay
. The overcurrent protec-
tion function is described in Chapter 5.16, page 188.
The overcurrent protection can be set to either a definite time or an inverse time char-
acteristic. This section summarizes those parameters which select the functions for
treating the phase and earth currents.
In this case the bay units need the specification of the rated system frequency.
5.14.2 Setting Notes
CHARAC. PH
The parameter
CHARAC. PH
(
7812/BU
)
is used to set the characteristic for the phase
currents of the overcurrent protection.
With setting
DEFINITE TIME
, a definite time characteristic will be used for the phase
current overcurrent protection (Chapter 5.16.1, page 188).
With setting
INVERSE TIME
, an inverse time characteristic will be used for the phase
current overcurrent protection (Chapter 5.16.1, page 188).
CHARAC. E
The parameter
CHARAC. E
(
7815/BU
)
is used to set the characteristic for the earth
currents of the overcurrent protection.
With setting
DEFINITE TIME
, a definite time characteristic will be used for the earth
current overcurrent protection (Chapter 5.16.1, page 188).
With setting
INVERSE TIME
, an inverse time characteristic will be used for the earth
current overcurrent protection (Chapter 5.16.1, page 188).
FREQUENCY
The parameter
FREQUENCY
(
7899/BU
)
is used to set the rated system frequency.
The default setting of
need only be changed in power systems with a rated fre-
quency of
.
Note
The parameter
FREQUENCY
(
7899/BU
) can only be set with the bay unit running in
stand-alone mode.
The value entered in the central unit for the parameter
5104/CU
) is not
affected by this.
With the bay unit linked to the central unit, the setting of this parameter is transmitted
from the central unit to the bay units. The local setting in the bay units is overwritten.
www
. com