Siemens 7SJ82, Manual

Page: 1257 / 1638

Structure of the Function
The Figure 9-10 shows the position of the function in the device. Every voltage measuring point contains the
Voltage-transformer circuit breaker function.
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Figure 9-10 Structure/Embedding of the Function
Function Description
The tripping of the voltage-transformer circuit breaker is captured via the binary input signal
>Open
. With an
active input signal the information about the measuring-voltage failure is relayed to the affected functions
(see
9.3.4.1 Overview of Functions ). The response to the detection of a measuring-voltage failure is explained
in the specific protection-function descriptions.
Response Time of the Voltage-Transformer Circuit Breaker
The response time of the voltage-transformer circuit breaker can be slower than the pickup time of the
distance protection. This bears the risk of an overfunction. The response time is communicated to the device
with the
Response time
parameter. For a timely detection of the tripping of the voltage-transformer circuit
breaker, the pickup of the distance protection is delayed by that response time.
Application and Setting Notes
The function is always active and need not be switched on.
Input Signal: >Open
•
Input signal:
(_:500) >Open
The input signal
>Open
must be connected to the tripping of the voltage-transformer circuit breaker. As a rule,
this occurs via the routing to a binary input.
Parameter: Response time of the voltage-transformer circuit breaker
•
Recommended setting value
(_:101) Response time
=
0 ms
When the voltage-transformer circuit breaker drops out, the device must block the distance protection imme-
diately to prevent an unwanted tripping of the distance protection due to the absence of the measuring
voltage while the load current is flowing.
The blocking must be faster than the 1st stage of the distance protection. This requires an extremely short
response time of the miniature circuit breaker (≤ 4 ms at 50 Hz, ≤ 3 ms at 60 Hz rated frequency). If the circuit-
breaker auxiliary contact does not fulfill this requirement, you have to set the response time accordingly.
Settings
Addr. Parameter C Setting Options Default Setting
VT miniatureCB
_:101 VT miniatureCB:Response
time 0.00 s to 0.03 s 0.00 s
9.3.4.2
9.3.4.3
9.3.4.4
9.3.4.5
Supervision Functions
9.3 Supervision of the Secondary System
SIPROTEC 5, Overcurrent Protection, Manual 1257
C53000-G5040-C017-8, Edition 07.2017