ABB RELION 650 SERIES, Applications Manual

Page: 36 / 262

Item Data
CT rated symmetrical short-circuit
current factor K
ssc
20
CT secondary winding resistance
R
ct
at
75
0
C
5 Ω
The rated equivalent secondary e.m.f. E
al
can now be calculated:
( ) ( )
1 20 5 25 600
al NS ssc ct b
E I K R R V
= × × + = × × + =
where I
NS
is the rated secondary current of the CT
145 kV VT ratio
145 0.11 0.11
/ /
3 3 3
kV
The high impedance differential protection needs dedicated CTs which have identical turns ratio
and similar magnetizing characteristics. Class TPS CTs, according to IEC 60044-6, and class PX
CTs, according to IEC 60044-1, are usually selected for this application. The class TPS CTs are used
in the following example.
Table 3: CT secondary wiring data
Item Data
Secondary CT conductor cross section
area
2.5 mm
2
Maximum length between bay and
protection
150 m
This gives the maximum secondary conductor resistance:
( )
( )
( )
2
sec
2
/
l m
R mm m
A mm
r
= W × ×
ϱ
CU = 0,0172 (Ω·mm
2
/m) at 20
°
C
ϱ
CU = 0,021 (Ω·mm
2
/m) at 75
°
C
R
sec
= 0,021 * 150 / 2,5 = 1,26 Ohm
Only settings that need adjustment due to the specific application are described in
setting examples. It is recommended to keep the default values for all settings that
are not described. Refer to Technical manual for setting tables for each protection
and control function.
For the functions not explained in the setting examples section, refer to the
Setting guidelines section of the corresponding function.
Use parameter setting tool in PCM600 to set the IED according to calculations for
the particular application.
The following protection functions are available:
Section 3 1MRK 505 287-UUS B
REB650 setting examples
30 Busbar protection REB650
Application manual
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