ABB 615 Series - Operation Principle

4.3.2.4 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.
BLK_OPR_LS
BLK_OPR_HS
Biased
low stage
Instantaneous
high stage
TRIP
OPR_LS
OPR_HS
BLKD2H
BLKD5H
BLKDWAV
OR
Compensation
of tap changer
position
Second
harmonic
blocking
Fifth harmonic
blocking
Waveform
blocking
Differential
calculation
Transformer
vector group
matching
Zero-
sequence
component
elimination
BLOCK
I_A1
I_B1
I_C1
I_A2
I_B2
I_C2
TAP_POS
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.
1MAC059074-MB A Section 4
Protection functions
615 series ANSI 501
Technical Manual