Scope Of Protective Functions In The Bay Unit - Siemens SIPROTEC 7SS523 V3.2 Manual

5.14

Scope of Protective Functions in the Bay Unit

5.14.1 Functional Description
5.14.2 Setting Notes
CHARAC. PH
CHARAC. E
FREQUENCY
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 Bay status (XX12/CU) to bay out of service. The overcurrent protec-
tion function is described in Chapter 5.16, page 185.
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.
The parameter CHARAC. PH (7812/BU
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 185).
With setting INVERSE TIME, an inverse time characteristic will be used for the phase
current overcurrent protection (Chapter 5.16.1, page 185).
The parameter CHARAC. E (7815/BU
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 185).
With setting INVERSE TIME, an inverse time characteristic will be used for the earth
current overcurrent protection (Chapter 5.16.1, page 185).
The parameter FREQUENCY (7899/BU
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 FREQUENCY (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.
The default setting of 50 Hz need only be changed in power systems with a rated fre-
quency of 60 Hz.
Scope of Protective Functions in the Bay Unit
is used to set the characteristic for the phase
)
is used to set the characteristic for the earth
)
is used to set the rated system frequency.
)
7SS52 V4 Manual
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