GE MiCOM P143 Agile User Manual

E00800
IED
S F
V
RES
=
Z
S0
2Z
S1
+ Z
S0
+ 2Z
L1
+ Z
L0
X 3 E
E
Z
S
Z
L
V
A
V
A
V
A
V
A
V
C
V
C
V
C
V
C
V
C
V
C
V
B
V
B
V
B
V
B
V
B
V
B
V
RES
V
RES
Figure 114: Residual voltage for a solidly earthed system
As can be seen from the abov
e diagram, the residual voltage measured on a solidly earthed system is solely
dependent on the ratio of source impedance behind the protection to the line impedance in front of the protection,
up to the point of fault. For a remote fault far away, the Z
S
/Z
L
: ratio will be small, resulting in a correspondingly
small residual voltage. Therefore, the protection only operates for faults up to a certain distance along the system.
The maximum distance depends on the device setting.
5.3.2 CALCULATION FOR IMPEDANCE EARTHED SYSTEMS
Consider a Phase-A to Earth fault on a simple radial system.
Chapter 10 - Voltage Protection Functions P14x
220 P14xEd1-TM-EN-1

GE MiCOM P143 Agile Specifications

General

Brand	GE
Model	MiCOM P143 Agile
Category	Control Unit
Language	English