ABB RELION 670 SERIES REG670 - Page 806

~
GDP
Ext fault
CT1 CT2
I
tf
I
tf
IEC11000215-1-en.vsd
IEC11000215 V1 EN-US
Figure 338:
Generator data:
Rated apparent power: 90 MVA
Rated voltage: 16 kV
Short circuit impedance: 25 %
The existing CTs (CT1 and CT2) have the following data:
•
CT1: 4000/1 A, 5P10, 15 V
A, the secondary winding resistance R
ct
= 5 Ω The
rated burden:
= = = W
b
2
sr
15 15
R 15
1
I
EQUATION2529 V2 EN-US (Equation 277)
• CT2: 4000/1 A, class PX, the rated knee point e.m.f. E
k
= 200 V, R
ct
= 5 Ω
From the data the E
al
can be calculated:
•
CT1:
( ) ( )
= × × + = × × + =
al sr ct b
E ALF I R R 10 1 5 15 200 V
EQUATION2530 V2 EN-US (Equation 278)
where ALF is the CT accuracy limit factor.
• CT2:
Section 24 1MRK 502 071-UUS A
Requirements
800 Generator protection REG670 2.2 ANSI and Injection equipment REX060, REX061, REX062
Application manual