Class Conversion; A.4.2 Class Conversion - Siemens SIPROTEC 7SJ62 Manual

A.4.2

Class conversion

Table A-1
British Standard BS 3938
ANSI/IEEE C 57.13, class C
IEC 60044-6 (transient response), class
TPS
Classes TPX, TPY, TPZ
SIPROTEC, 7SJ62/64, Manual
C53000-G1140-C207-2, Release date 01.2008
Conversion into other classes
= 5 A (typical value)
I
sNom
K≈ 1
≈ K
K
SSC ALF
Calculation See ChapterA.4.1 Accuracy limiting factors with: K
n
T depending on power system and specified closing sequence
P
with
V Knee-point voltage
k
R Internal burden resistance
Ct
R Nominal burden resistance
BN
secondary nominal transformer current
I
sNom
K Rated accuracy limiting factor
ALF
V sec. terminal volt. at 20 I
s.t.max
V sec. magnetization limit voltage
al
K Dimensioning factor
K Factor symmetr. Rated fault current
SSC
T Primary time constant
P
Appendix
A.4 Current Transformer Requirements
pNom
≈
SSC
613