ABB RELION RET670 User Manual

high which limits the zero sequence current on the parallel line to very low values. In
practice, the equivalent zero sequence impedance circuit for faults at the remote bus
bar can be simplified to the circuit shown in figure 158
The line zero sequence mutual impedance does not influence the measurement of the
distance protection in a faulty circuit.
A
B
C
IEC09000255_1_en.vsd
I
0
I
0
Z
0m
Z
0
-
Z
0m
Z
0m
Z
0
-
IEC09000255 V1 EN-US
Figure 159: Equivalent zero sequence impedance circuit for a double-circuit line
with one circuit disconnected and not grounded.
8.9.2.7 Tapped line application
GUID-1230B60C-8C3C-4405-8209-E089CAF07847 v1
C
A
B
BC
ANSI05000224-2-en.vsd
ANSI05000224 V2 EN-US
Figure 160: Example of tapped line with Auto transformer.
This application gives rise to similar problem that was highlighted in section
"Fault
infeed from remote end" , that is increased measured impedance due to fault current
1MRK 504 163-UUS A Section 8
Impedance protection
Transformer protection RET670 2.2 ANSI 335
Application manual

ABB RELION RET670 Specifications

General

Brand	ABB
Model	RELION RET670
Category	Protection Device
Language	English