Controlling Protection Elements - Siemens SIPROTEC 4 7SJ61 Manual

Circuit Breaker Monitoring
The time needed by the circuit breaker to perform a complete reclose cycle can be monitored by the 7SJ61.
Breaker failure is detected:
A precondition for a reclosing attempt, following a trip command initiated by a protective relay element and
subsequent initiation of the automatic reclosing function, is that the circuit breaker is ready for at least one
TRIP-CLOSE-TRIP cycle. The readiness of the circuit breaker is monitored by the device using a binary input
Ready . In the case where this signal from the breaker is not available, the circuit breaker monitoring feature
should be disabled, otherwise reclosing attempts will remain blocked.
•
Especially when multiple reclosing attempts are programmed, it is a good idea to monitor the circuit
breaker condition not only prior to the first but also to each reclosing attempt. A reclosing attempt will be
blocked until the binary input indicates that the circuit breaker is ready to complete another CLOSE-TRIP
cycle.
•
The time needed by the circuit-breaker to regain the ready state can be monitored by the 7SJ61. The
monitoring time CB TIME OUT expires for as long as the circuit breaker does not indicate that it is ready
via binary input
monitoring time CB TIME OUT is started. If the binary input returns before the monitoring time has
elapsed, the monitoring time will be canceled and the reclosure process is continued. If the monitoring
time runs longer than the dead time, the dead time will be extended accordingly. If the monitoring time
elapses before the circuit breaker signals its readiness, the automatic reclosure function will be blocked
dynamically.
Interaction with the synchronism check may cause the dead time to extend inadmissibly. To prevent the auto-
matic reclosure function from remaining in an undefined state, dead time extension is monitored. The
maximum extension of the dead time can be set at Max. DEAD EXT.. The monitoring time Max. DEAD
EXT. is started when the regular dead time has elapsed. If the synchronism check responds before the time
has elapsed, the monitoring time will be stopped and the close command generated. If the time expires before
the synchronism check reacts, the automatic reclosure function will be blocked dynamically.
Please make sure that the above mentioned time is not shorter than the monitoring time CB TIME OUT.
The time 7114 T-Start MONITOR serves for monitoring the response of the automatic reclosure function to
a breaker failure. It is activated by a trip command arriving before or during a reclosing operation and marks
the time that passes between tripping and opening of the circuit breaker. If the time elapses, the device
assumes a breaker failure and the automatic reclosure function is blocked dynamically. If parameter T-Start
MONITOR is set to ∞, the start monitoring is disabled.
2.11.4

Controlling Protection Elements

Depending on the reclosing cycle it is possible to control elements of the directional and non-directional over-
current protection by means of the automatic reclosure system (Protective Elements Control). There are three
mechanisms:
•
Time overcurrent protection and the sensitive ground fault protection elements may trip instantaneously
depending on the automatic reclosure cycle (T = 0), they may remain unaffected by the auto reclosing
function AR (T = T) or may be blocked (T = ∞). For further information see side title "Cyclic Control".
•
The automatic reclosing states "Auto Reclosing ready" and "Auto Reclosing not ready" can activate or
deactivate the dynamic cold load pickup function. This function is designed to influence overcurrent
stages (see also Section 2.16.6 and Section
delays.
•
The time overcurrent protection parameter 1X14A 50(N)-2 ACTIVE or 1X16A 50(N)-3 ACTIVE defines
whether the elements 50(N)-2 or 50(N)-3 are to operate always or only with "79M Auto Reclosing
ready"(see Section
Cyclic Control
Control of the time overcurrent protection and sensitive ground fault protection elements takes effect by
releasing the cycle marked by the corresponding parameter. The cycle zone release is indicated by the
messages 79 1.CycZoneRel to 79 4.CycZoneRel . If the automatic reclosure function is in normal state,
SIPROTEC 4, 7SJ61, Manual
C53000-G1140-C210-6, Edition 05.2016
>CB Ready (FNo. 2730). That means if the binary input >CB Ready is cleared, the
2.2 Overcurrent Protection 50, 51, 50N,
2.11.6 Setting Notes) regarding thresholds and tripping time
51N).
Functions
2.11 Automatic Reclosing System 79
>CB
153