ABB RELION RET670 User Manual

From symmetrical components, we can derive the impedance Z at the relay point for
normal lines without mutual coupling according to equation 117.
ph ph
0 1 ph N
ph 0
1
0
V V
Z Z I 3 K
I 3I
3 Z
I
Z = =
- + ×
+ ×
×
EQUATION1275 V3 EN-US (Equation 117)
Where:
Vph is phase to ground voltage at the relay point
Iph is phase current in the faulty phase
3I0 is ground fault current
Z1 is positive sequence impedance
Z0 is zero sequence impedance
Z0m
A B
21 21
en05000221_ansi.vsd
FAULT
ANSI05000221 V1 EN-US
Figure 125: Class 1, parallel line in service
The equivalent circuit of the lines can be simplified, see figure
126.
A
B
C
Z
0m
Z
0m
Z
0
-
Z
0m
Z
0
-
IEC09000253_1_en.vsd
IEC09000253 V1 EN-US
Figure 126: Equivalent zero sequence impedance circuit of the double-circuit,
parallel, operating line with a single phase-to-ground fault at the
remote busbar
1MRK 504 163-UUS A Section 8
Impedance protection
Transformer protection RET670 2.2 ANSI 267
Application manual

ABB RELION RET670 Specifications

General

Rated Frequency	50/60 Hz
Communication Protocols	IEC 61850, IEC 60870-5-103, DNP3
Operating Temperature Range	-25°C to +55°C
Mounting	Rack Mounting
Input Voltage	100-240 V AC
Protection Functions	Overcurrent Protection
Enclosure	IP20