Functions
2.6 Voltage Protection 27, 59
SIPROTEC, 7SJ62/64, Manual
C53000-G1140-C207-2, Release date 01.2008
144
Figure 2-47 Typical fault profile for load side connection of the voltage transformers
(with current supervision)
Upon the closing of the circuit breaker, current criterion is delayed for a short period of time. If the voltage cri-
terion drops out during this time period (about 60 ms), the protection function does not pick up. Thereby no fault
record is created when voltage protection is activated in a healthy system. It is important to understand, how-
ever, that if a low voltage condition exists on the load after the circuit breaker is closed (unlike Figure 2-47), the
desired pickup of the element will be delayed by 60 ms.
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