
Functions
2.11 Automatic Reclosing System 79
SIPROTEC, 7SJ61, Manual
C53000-G1140-C210-1, Release date 02.2008
172
Example:
Before the first reclosing, faults are to be eliminated quickly applying elements 50-2 or 50N-2. Fast fault termi-
nation thus has priority over selectivity aspects as the reclosing action aims at maintaining normal system op-
eration. If the fault prevails, a second tripping is to take place instantaneously and subsequently, a second re-
closing.
After the second reclosing, however, elements 50-2 or 50N-2 are to be blocked so the fault can be eliminated
by applying elements 50-1 or 50N-1 according to the grading coordination chart of the system giving priority to
selectivity concerns.
Addresses
7202
bef.1.Cy:50-2
,
7214
bef.2.Cy:50-2
,
7203
bef.1.Cy:50N-2
and
7215
bef.2.Cy:50N-2
are set to
instant. T=0
to enable the elements after the first reclosing. Addresses
7226
bef.3.Cy:50-2
and
7227
bef.3.Cy:50N-2
, however, are set to
blocked T=
∞
, to ensure that elements
50-2 and 50N-2 are blocked when the second reclosing applies. The back-up elements, e.g. 50-1 and 50N-1,
must obviously not be blocked (addresses
7200
,
7201
,
7212
,
7213
,
7224
and
7225
).
The blocking applies only after reclosure in accordance with the set address. Hence, it is possible to specify
again other conditions for a third reclosure.
The blocking conditions are also valid for the zone sequence coordination, provided it is available and activated
(address
7140
, see also margin heading "Zone Sequencing").
2.11.5
Zone Sequencing (not available for models 7SJ6***-**A**-)
It is the task of the zone sequence coordination to harmonize the automatic reclosure function of this device
with that of another device that forms part of the same power system. It is a complementary function to the
automatic reclosure program and allows, for example, to perform group reclosing operations in radial systems.
In case of multiple reclosures, groups may also be in nested arrangement and further high-voltage fuses can
be overgraded or undergraded.
Zone sequencing functions by means of blocking certain protection functions depending on the reclosing cycle.
This is implemented by the protection elements control (see margin heading "Controlling Protection Ele-
ments").
As a special feature, changing from one reclosing cycle to the next is possible without trip command only via
pickup/dropout of 50-1 or 50N-1.
The following figure shows an example of a group reclosure at feeder 3. It is assumed that reclosure is per-
formed twice.
With fault F1 on feeder 5, protection devices in the infeed and on feeder 3 pick up. The time delay of the 50-2
element at protecting feeder 3 is set in such a way that the feeder 3 circuit breaker will clear the fault before the
fuse at feeder 5 is damaged. If the fault is cleared, all functions are reset after the restraint time has expired
and the fault is terminated. The fuse has therefore also been protected.
If the fault continues to exist, a second reclosing cycle is performed in the same way.
High speed element 50-2 is now being blocked at relay protecting Feeder 3. If the fault still remains, only the
50-1 element continues to be active in Feeder 3 which, however,
overgrades
the fuse with a time delay of 0.4
s. After the fuse operated to clear the fault, the series-connected devices drop out. If the fuse fails to clear the
fault, then the 50-1 element protecting Feeder 3 will operate as backup protection.
The 50-2 element at the busbar relay is set with a delay of 0.4 seconds, since it supposed to trip the 50-2 ele-
ments and the fuses as well. For the second reclosing, the 50-2 element also has to be blocked to give prefer-
ence to the feeder relay (50-1 element with 0.4 s). For this purpose, the device has to "know" that two reclosing
attempts have already been performed.
In this device, zone sequence coordination must be switched off: When pickup of 50-1 or 50N-1 drops out, zone
sequence coordination provokes that the reclosing attempts are counted as well. If the fault still persists after
the second reclosure, the 50-1 element, which is set to 0.9 seconds, would serve as backup protection.
Содержание SIPROTEC 7SJ61
Страница 368: ...Technical Data 4 22 Dimensions SIPROTEC 7SJ61 Manual C53000 G1140 C210 1 Release date 02 2008 368 ...
Страница 436: ...Appendix A 11 Measured Values SIPROTEC 7SJ61 Manual C53000 G1140 C210 1 Release date 02 2008 436 ...
Страница 438: ...Literature SIPROTEC 7SJ61 Manual C53000 G1140 C210 1 Release date 02 2008 438 ...
Страница 450: ...Glossary SIPROTEC 7SJ61 Manual C53000 G1140 C210 1 Release date 02 2008 450 ...
Страница 454: ...Index SIPROTEC 7SJ61 Manual C53000 G1140 C210 1 Release date 02 2008 454 ...