Operation Principle - ABB 615 series Technical Manual

1MAC059074-MB A
4.3.2.4
615 series ANSI
Technical Manual

Operation principle

The function can be enabled and disabled with the Operation setting. The corresponding
parameter values are "Enable" and "Disable".
The operation of 87T can be described by using a module diagram. All the modules in the
diagram are explained in the next sections.
Differential
calculation
I_A1
Transformer
I_B1
vector group
matching
I_C1
I_A2
sequence
I_B2
component
elimination
I_C2
TAP_POS
Compensation
of tap changer
position
BLK_OPR_HS
BLOCK
BLK_OPR_LS
Second
harmonic
blocking
Fifth harmonic
blocking
Waveform
blocking
GUID-C4FFDFA8-A197-4983-87D4-A6A426FE1BF1 V1 EN
Figure 248: Functional module diagram
Differential calculation
87T operates phase-wise on a difference of incoming and outgoing currents. The positive
direction of the currents is towards the protected object.
Instantaneous
Zero-
high stage
Biased
low stage
Section 4
Protection functions
OR TRIP
OPR_LS
OPR_HS
BLKD2H
BLKD5H
BLKDWAV
501