Siemens 7SJ85 - Application and Setting Notes

Application and Setting Notes
Interface to the Circuit-Breaker Function Group
The Capacitor bank side function group is usually connected to 1 Circuit-breaker function group. The
Circuit-breaker function group is assigned to the circuit breaker of the capacitor bank.
Parameter: Rated apparent power
•
Default setting (_:1781:15571:103) Rated apparent power = 692.82 MVA.
The Rated apparent power parameter shows the primary rated apparent power of the capacitor
bank to be protected. The setting value is determined of the Capacitor reference volt. and the
Capacitor reference curr. parameters.
Parameter: Capacitor reference volt.
•
Default setting (_:1781:15571:102) Capacitor reference volt. = 400.00 kV
You can use the Capacitor reference volt. parameter to set the reference voltage of the capacitor
bank to be protected. The reference voltage set here is the reference value for the percentage measured
values and setting values made in percent.
Depending on user philosophy you can use the system rated voltage (busbar voltage) or the capacitor rated
voltage as a reference value.
Parameter: Capacitor reference curr.
•
Default setting (_:1781:15571:101) Capacitor reference curr. = 1000 A
You can use the Capacitor reference curr. parameter to set the reference current for the capacitor
bank to be protected. The capacitor reference current set here is the reference value for the percentage meas-
ured values and setting values in percent.
For Differential protection, these values are used for absolute-value correction (rated current of the protected
object).
If the capacitor bank is part of a delta connection, the value to be set here can differ from the capacitor refer-
ence current set in the Capacitor bank function group (by factor √3). Otherwise, set always the same values.
Depending on user philosophy, you can use the capacitor-bank rated current including the harmonics or the
capacitor-bank fundamental-component current as a reference value.
Parameter: Neutral point
•
Default setting (_:1781:15571:149) Neutral point = isolated
With the Neutral point parameter, you specify whether the neutral point in the protection range of the
differential protection is grounded or isolated. If there is no neutral point in the protection zone, use the
parameter isolated. The neutral point of a capacitor bank is usually not in the protection zone. Therefore,
even if the neutral point is grounded, set isolated here.
You can find further information in the Device manual 7UT8 Chapter 6.2.3 function description neutral point-
current handling.
Parameter: Winding configuration
•
Default setting (_:1781:15571:104) Winding configuration = Y (Wye)
You can use the Winding configuration parameter to set D (Delta) for a delta connection. Another
setting option is Y (Wye) for a star connection. The Winding configuration parameter is relevant for
the Differential protection function.
Parameter: Vector group numeral
•
Default setting (_:1781:15571:100) Vector group numeral = 0
This parameter is used to account for phase-angle rotation, which is expressed by a numeral.
5.5.3.3
Function-Group Types
5.5 Function-Group Type Capacitor Bank Differential Protection
234 SIPROTEC 5, Overcurrent Protection, Manual
C53000-G5040-C017-8, Edition 07.2017