Siemens SIPROTEC 4, User Manual

Page: 243 / 734

•
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 7SJ62/64. The
monitoring time
CB TIME OUT
expires for as long as the circuit breaker does not indicate that it is ready
via binary input
>CB Ready
(FNo. 2730). That means if the binary input
>CB Ready
is cleared, the
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.
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
2.16.6 Setting Notes ) regarding thresholds and tripping time
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
2.2 Overcurrent Protection 50, 51, 50N, 51N ).
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,
the settings for the starting cycle apply. These settings always take effect when the automatic reclosure func-
tion assumes normal state.
The settings are released for each following cycle when issuing the close command and starting the blocking
time. Following a successful reclosure (blocking time expired) or after returning from the blocking, the auto-
matic reclosure function goes into normal state. Control of the protection is again assumed by the parameters
for the starting cycle.
The following figure illustrates the control of the protection elements 50-2 and 50N-2.
2.16.4
Functions
2.16 Automatic Reclosing System 79
SIPROTEC 4, 7SJ62/64, Manual 243
C53000-G1140-C207-8, Edition 08.2016