Siemens siprotec SJ62 User Manual page 248

Zone Sequencing
Controlling Direc-
tional / Non-Direc-
tional Overcurrent
Protection Ele-
ments via Cold
Load Pickup
SIPROTEC 4, 7SJ62/63/64 Handbuch
C53000-G1140-C147-A, Edition 07.2015
Not available for models 7SJ62/63/64**-**A**-
At address 7140 ZONE SEQ.COORD., the zone sequencing feature can be turned ON
or OFF.
If multiple reclosures are performed and the zone sequencing function is deactivated,
only those reclosing cycles are counted which the device has conducted after a trip
command. With the zone sequencing function switched on, an additional sequence
counter also counts such auto-reclosures which (in radial systems) are carried out by
relays connected on load side. This presupposes that the pickup of the 50-1/50N-1 el-
ements drops out without a trip command being issued by a protective function initiat-
ing the auto-reclose function. The parameters at addresses 7200 through 7247 (see
paragraph below at "Initiation and Blocking of Reclosing by Protective Functions" and
"Controlling Directional/Non-Directional Overcurrent Protection Stages via Cold Load
Pickup") can thus be set to determine which protective elements are active or blocked
during what dead time cycles (for multiple reclosing attempts carried out by relays on
the load side).
In the example shown in Figure 2-52 "Zone sequencing with a fault occurring at Tap
Line #5 and the busbar" in the functional description, the zone sequencing was applied
in the bus relay. Moreover, the 50-2 elements would have to be blocked after the
second reclosure, i.e. address 7214 bef.2.Cy:50-2 is to be set to blocked T=∞.
The zone sequencing of the feeder relays is switched off but the 50-2 elements must
also be blocked here after the second reclosing attempt. Moreover, it must be ensured
that the 50-2 elements start the automatic reclosing function: address 7152 50-2 set
to Starts 79.
The cold load pickup function provides a further alternative to control the protection via
the automatic reclosing system (see also Section 2.4). This function provides the
address 1702 Start Condition It determines the starting conditions for the in-
creased setting values of current and time of the cold load pickup that must apply for
directional and non-directional overcurrent protection.
If address 1702 Start Condition = 79 ready, the directional and non-directional
overcurrent protection always employ the increased setting values if the automatic re-
closing system is ready. The auto-reclosure function provides the signal 79 ready for
controlling the cold load pickup. The signal 79 ready is always active if the auto-re-
closing system is available, active, unblocked and ready for another cycle. Control via
the cold load pickup function is non-cyclic.
Since control via cold load pickup and cyclic control via auto-reclosing system can run
simultaneously, the directional and non-directional overcurrent protection must coor-
dinate the input values of the two interfaces. In this context the cyclic auto-reclosing
control has the priority and thus overwrites the release of the cold load pickup function.
If the protective elements are controlled via the automatic reclosing function, changing
the control variables (e.g. by blocking) has no effect on elements that are already run-
ning. The elements in question are continued.
2.14 Automatic Reclosing System 79
246