Supervision of the Secondary System
Overview
The secondary circuits establish a connection to the power system from the point of view of the device. The
measuring-input circuit (currents, voltages) as well as the command circuits to the circuit breakers are moni-
tored for the correct function of the device. The connection to the station battery is ensured with the supervi-
sion of the external auxiliary voltage. The secondary system has the following supervision systems:
Measuring circuits (voltage):
•
Measuring-voltage failure
•
Voltage-transformer circuit breaker
•
Voltage balance
•
Voltage sum
•
Voltage rotating field
Measuring circuits (current):
•
Broken conductor of the current circuits
•
Current balance
•
Current sum
•
Current rotating field
Trip circuits
External auxiliary voltage
When these supervisions pick up, corresponding warning indications are output. Some supervisions lead
directly to the blocking of affected protection functions or to the marking of measuring points that have
become invalid, so that affected protection functions can go into a secure state.
A detailed description of the supervision mechanisms and their error responses can be found in the Function
Description and as overall overview at the end of chapter 8.
Measuring-Voltage Failure
Overview of Functions
The Measuring-voltage failure detection function monitors the voltage transformer secondary circuits:
•
Non-connected transformers
•
Pickup of the voltage transformer circuit breaker (in the event of short circuits in the secondary circuit)
•
Broken conductor in one or more measuring loops
All these events cause a voltage of 0 in the voltage transformer secondary circuits which can lead to failures of
the protection functions.
For the following protection functions, the response (block/not block) to a measuring-voltage failure can be
set within the function:
•
Overvoltage protection with negative-sequence voltage
•
Overvoltage protection with zero-sequence voltage/residual voltage
•
Undervoltage protection with 3-phase voltage
•
Undervoltage protection with positive-sequence voltage
8.3
8.3.1
8.3.2
8.3.2.1
Supervision Functions
8.3 Supervision of the Secondary System
938 SIPROTEC 5, High-Voltage Bay Controller, Manual
C53000-G5040-C015-9, Edition 11.2017
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