Table of Contents
Advertisement
signal. Figure 2-41 illustrates the functional principle. If the breaker failure protection is initiated and current flow
is detected (current criteria „L*> current criterion" according to Figure 2-29), but no circuit breaker pole is closed
(auxiliary contact criterion „ any pole closed"), then the timer T-EndFault is started. At the end of this time an
intertrip signal is transmitted to the opposite end(s) of the protected object.
Figure 2-41
Pole discrepancy supervision
The pole discrepancy supervision has the task to detect discrepancies in the position of the three circuit breaker
poles. Under steady-state operating conditions, either all three poles of the breaker must be closed, or all three
poles must be open. Discrepancy is permitted only for a short time interval during a single-pole automatic
reclose cycle.
The scheme functionality is shown in Figure 2-42. The signals which are processed here are the same as those
used for the breaker failure protection. The pole discrepancy condition is established when at least one pole is
closed („ ≥ one pole closed") and at the same time not all three poles are closed („ ≥ one pole open").
Additionally, the current criteria (from Figure 2-29) are processed. Pole discrepancy can only be detected when
current is not flowing through all three poles, i.e. through only one or two poles. When current is flowing through
all three poles, all three poles must be closed even if the breaker auxiliary contacts indicate a different status.
If pole discrepancy is detected, this is indicated by a fault detection signal. This signal identifies the pole which
was open before the trip command of the pole discrepancy supervision occurred.
Figure 2-42
SIPROTEC, 7VK61, Manual
C53000-G1176-C159-3, Release date 05.2009
Operation scheme of end fault protection
Function diagram of pole discrepancy supervision
2.6 Circuit breaker failure protection (optional)
Functions
125
Advertisement
Table of Contents
