Functions
2.11 Monitoring Functions
SIPROTEC, 7SJ62/64, Manual
C53000-G1140-C207-2, Release date 01.2008
207
2.11.1.7 Broken Wire Monitoring of Voltage Transformer Circuits
Requirements
This function is only available in device version „World“ (Ordering Information Pos. 10 = B), as it is only used
in certain regions. Furthermore, the measurement of all three phase-to-ground voltages is a requirement. If only
two phase-to-phase voltages were measured, it would not be possible to evaluate two of the required criteria.
Task
The broken wire monitoring function monitors the voltage transformer circuits of the secondary system with
regard to failure. One distinguishes between single-pole, two-pole and three-pole failures.
Mode of Operation / Logic
All three phase-to-ground voltages, the displacement voltage and the three phase currents are measured. The
required values are calculated for the respective criteria and eventually a decision is made. The resulting alarm
message may be delayed. A blocking of the protection functions is however not effected. This is done by the
measuring voltage failure detection.
The broken wire monitoring is also active during a fault. The function may be enabled or disabled.
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