Accuracy Limiting Factors - Siemens SIPROTEC 4 User Manual

Current Transformer Requirements
D.1 Accuracy limiting factors
D.1

Accuracy limiting factors

Betriebs- und Nennüberstromziffer
Required minimum effective accuracy limiting
factor
Resulting rated accuracy limiting factor
Calculation example according to IEC 60044–1
= 1 A
Ι
sNom
K = 20
ALF
R = 0.6 Ω (device and cables)
BC
R = 3 Ω
Ct
R = 5 Ω (5 VA)
BN
mit
= secondary transformer nominal current
Ι
sNom
596
but at least 20
mit
n' Minimum effective accuracy limiting factor
Primary pickup value of the high-current
Ι>>
Anr
element
Primary nominal transformer current
Ι
pN
with
K Rated accuracy limiting factor
ALF
R Connected burden resistance (device and
BC
cables)
R Nominal burden resistance
BN
R Transformer internal burden resistance
Ct
K set to 10,
ALF
so that: 5P10, 5 VA
C53000-G1140-C207-8, Edition 08.2016
SIPROTEC 4, 7SJ62/64, Manual