ADR233B
Ref ID : ADR233B/IM/PS
Rev No. : 05
Page No. : 132 of 479
Case 1: Blocking function can be activated by enabling “Hrm Blk Mode” setting as 2H in relay.
The ADR233B relay provides 2
nd
harmonic blocking feature to block the differential tripping
during transformer energisation on normal condition. The device is determining the fundamental
I(fn) and Second harmonic Components I (2*fn) of the differential current. If the ratio I
(2*fn)/I(fn) exceeds a specific adjustable value (typical setting 20%) in at least one measuring
system, Differential tripping is Blocked.
ADR233B relay provides the “Cross Blocking” criteria/logic can be enabling or disabling / timer
through the software in the relay. The relay provides phase segregated blocking logic if the
cross blocking disabled.
2H Diff Threshold
2H current
+
-
&
Diff L1 T
Hr m BL k Mod e =2H
2HDif-A B
&
Cr oss B lo cking =
Enabled
2HDif-B B
2HDif-C B
Cr oss B lo cking = Timer
or
+
-
t Cross
blocking= 0.5s
Time measure from
any p hase 2
nd
hrm
detection
&
Figure 8: Harmonic blocking (only 2
nd
Harmonic)
Harmonic blocking logic for B phase and C Phase Also Same like Harmonic blocking logic of A Phase
Case 2: Blocking function can be activated by enabling “Hrm Blk Mode” setting as 2H&4H in
relay. In this case ADR233B relay check the following two conditions must be asserted
simultaneously
1) The device is determining the fundamental I(fn) and Second harmonic components I (2*fn)
of the differential current. If the ratio I (2*fn)/I(fn) exceeds a specific adjustable value (typical
setting 20%) in at least one measuring system.
2) The device is determining the fundamental I(fn) and forth harmonic Components I (4*fn) of
the differential current. If the ratio I (4*fn)/I(fn) exceeds a specific adjustable value (typical
setting 20%)
ADR233B relay provides the “Cross Blocking” criteria/logic can be enabling or disabling
through the software in the relay. The relay provides phase segregated blocking logic if the
cross blocking disabled.
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