GE MiCOM P141 Agile - High Impedance REF Protection Application; High Impedance REF Operating Modes; Figure 98: Hi-Z REF Protection for a Grounded Star Winding; Figure 99: Hi-Z REF Protection for a Delta Winding

4.3 HIGH IMPEDANCE REF PROTECTION APPLICATION
4.3.1 HIGH IMPEDANCE REF OPERATING MODES
In the examples below, the respective Line CTS and measurement CTs must have the same CT ratios and similar
magnetising characteristics.
a
b
c
C
A
B
Rst
TN
1 CT
TN2 CT
TN3 CT
Varistor
CT1
CT
N
V00684
Figure 98: Hi-Z REF protection for a grounded star winding
a
b
c
C
A
B
Varistor
Rst
CT
1
V00685
TN 1 CT
TN
2 CT
TN 3 CT
Figure 99: Hi-Z REF protection for a delta winding
P14x Chapter 7 - Restricted Earth Fault Protection
P14xEd1-TM-EN-1 177