ABB RET670 - Setting Guidelines

3.6.11.2 Setting guidelines
Setting guidelines are prepared in the form of a setting example for the protected power
line as part of a two-machine system presented in figure 160.
99001019_ansi.vsd
~~
E
A
d
A
= const
d
B
= f(t)
E
B
A B
Z
SA
Z
SB
Z
L
R
ANSI99001019 V1 EN
Figure 160: Protected power line as part of a two-machine system
Reduce the power system with protected power line into equivalent two-machine
system with positive sequence source impedances Z
SA
behind the IED and Z
SB
behind
the remote end bus B. Observe a fact that these impedances can not be directly
calculated from the maximum three-phase short circuit currents for faults on the
corresponding busbar. It is necessary to consider separate contributions of different
connected circuits.
The required data is as follows:
400
r
V kV=
EQUATION1728 V1 EN
Rated system voltage
min
380V kV=
EQUATION1729 V1 EN
Minimum expected system voltage under critical system
conditions
60
n
f Hz=
EQUATION1730 V1 EN
Rated system frequency
400
3
p
V kV=
EQUATION1731 V1 EN
Rated primary voltage of voltage protection transformers used
0.115
3
s
V kV=
EQUATION1732 V1 EN
Rated secondary voltage of voltage instrument transformers used
Table continues on next page
Section 3 1MRK504116-UUS C
IED application
358
Application manual