Accuracy Limiting Factors - Siemens 7SC80 Manual

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

Accuracy limiting factors

Effective and Rated Accuracy Limiting Factor
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
with
= secondary transformer nominal current
Ι
sNom
606
but at least 20
with
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
E50417-G1140-C486-A8, Edition 07.2017
SIPROTEC Compact, 7SC80, Manual