ABB RELION 620 Series Technical Manual page 429

1MAC504801-IB E
620 series ANSI
Technical Manual
I_A1
I_B1
Transformer
vector group
I_C1
I_A2
I_B2
I_C2
I_A3
Compensation
I_B3
of tap changer
I_C3
BLK_OPR_HS
BLOCK
BLK_OPR_LS
Fifth harmonic
GUID-51BB01EB-D586-436D-969A-0BDCC92D4CD4 V1 EN
Figure 193: Functional module diagram. I_x1, I_x2 and I_x3 represent phase currents
of winding 1, winding 2 and winding 3 or restraint of winding 1 or 2.
Differential calculation
87T operates phasewise on the difference of incoming and outgoing currents. The positive
direction of the currents is towards the protected object
Differential
calculation
matching
Instantaneous
Zero-
high stage
sequence
component
elimination
position
Second
harmonic
blocking
Biased
low stage
blocking
Waveform
blocking
Section 4
Protection functions
OR TRIP
OPR_LS
OPR_HS
BLKD2H
BLKD5H
BLKDWAV
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