Blocking the Stage
In the event of blocking, the picked up stage will be reset. The following blocking options are available for the
stage:
•
Via the binary input signal
>Block stage
from an external or internal source.
•
From inside on pickup of the Measuring-voltage failure detection function (see section 9.3.2.1 Over-
view of Functions). The parameter Blk. by meas.-volt. failure can be set so that the meas-
uring-voltage failure detection blocks the stage or does not block it.
•
From an external source via the binary input signal
>Open
of the Volt.-transf. c. b. function block, which
links in the tripping of the voltage-transformer circuit breaker. The parameter Blk. by meas.-volt.
failure can be set so that the measuring-voltage failure detection blocks the stage or does not block it.
Application and Setting Notes
Parameter: Threshold
•
Default setting (_:15811:3) Threshold = 0.200 p.u.
The parameter Threshold is set as a p.u. value related to the parameter Capacitor bank reference
voltage in the Capacitor bank function group.
The setting of the parameter Threshold depends on the differential voltage that occurs with the number of
defective C elements for which a warning indication or a trip command shall be generated. Determine this
differential voltage and set the Threshold slightly lower, for example, to 80 % of the value.
Parameter: Operate delay
•
Default setting (_:15811:6) Operate delay = 1.00 s
Set the parameter Operate delay for the specific application.
Parameter: Blk. by meas.-volt. failure
•
Default setting (_:15811:10) Blk. by meas.-volt. failure = yes
You can use the parameter Blk. by meas.-volt. failure to control the response of the stage when a
measuring-voltage failure is detected.
A measuring-voltage failure can only be detected if one of the following 2 conditions is met:
•
The device-internal Measuring-voltage failure detection function is configured and switched on.
•
The binary input signal
>Open
of the Voltage-transformer circuit breaker function block is connected to
the voltage-transformer circuit breaker. This binary input is available in the voltage transformers
connected to the bus voltage and capacitor-bank tap voltage. The binary input is also available in the
voltage transformer connected to the VN voltage in case of an isolated capacitor bank.
Parameter Value
Description
no
The stage Vdiff> is not blocked when a measuring-voltage failure is detected.
yes
The stage Vdiff> is blocked when a measuring-voltage failure is detected.
Siemens recommends using the default setting, as correct operation of the
stage cannot be guaranteed if a measuring-voltage failure occurs.
Settings
Addr.
Parameter C Setting Options Default Setting
General
_:15781:102 General:Matching-factor
setting
•
not phase-selective
•
phase-selective
not phase-selec-
tive
_:15781:101 General:Voltage
matching factor
0.5000 to 2000.0000 2.0000
7.7.4.2
7.7.4.3
Capacitor Bank Protection
7.7 Voltage Differential Protection for Capacitors
SIPROTEC 5, Overcurrent Protection, Manual 1041
C53000-G5040-C017-8, Edition 07.2017
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