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Section 6
Differential protection
•
included to the differential zone A when input signal CTRLZA on corresponding bay block
is given logical value one and it will be excluded from the differential zone A when input
signal CTRLZA on corresponding bay block is given logical value zero.
•
included to the differential zone B when input signal CTRLZB on corresponding bay block
is given logical value one and it will be excluded from the differential zone B when input
signal CTRLZB on corresponding bay block is given logical value zero.
This setting is typically used for feeder bays in double busbar stations in order to form proper
busbar disconnector replica. It is especially suitable both when normally open and normally
closed (that is, "a" and "b" contacts) auxiliary contacts from the busbar disconnectors are
available to the IED.
If for a particular CT input setting parameter
will be:
•
excluded from the differential zone A when input signal CTRLZA on corresponding bay
block is given logical value one and it will be included to the differential zone A when input
signal CTRLZA on corresponding bay block is given logical value zero
•
excluded from the differential zone B when input signal CTRLZB on corresponding bay
block is given logical value one and it will be included to the differential zone B when input
signal CTRLZB on corresponding bay block is given logical value zero.
This setting is typically used for feeder bays in double busbar single breaker stations in order
to form proper busbar disconnector replica. It is especially suitable when only normally closed
(that is, "b" contact) auxiliary contact from the busbar disconnector(s) is available to the IED.
For more information please refer to Figure 63.
6.1.3.6
CT disconnection for bus interconnector CT cores
For simplicity purpose, sometimes we also refer to a bus-section or bus-coupler bay as a bus
interconnector bay. In practice there are three different solutions for bus interconnector bay
layout. First solution is with two sets of main CTs, which are located on both sides of the
circuit breaker, as shown in Figure 45.
IEC01000013 V1 EN-US
Figure 45: Example of station with two sets of main CTs in the bus-section bay
Two differential zones are overlapping across the bus-section or bus-coupler circuit breaker.
All faults in the overlapping zone will be instantly tripped by both zones irrespective of the
section/coupler circuit breaker status. However with modern busbar protection it is possible
to disconnect both CTs from the relevant zones when the bus-section or bus-coupler circuit
102
ZA
1
2
8
ZoneSel is set to Ctrl_Excludes , then this CT input
ZB
BS
1
2
1MRK 505 370-UEN D
8
en01000013.vsd
Busbar protection REB670
Application manual
M12113-3 v4
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