Areva MiCOM P441, Technical Manual

Page: 283 / 636

Application Notes P44x/EN AP/E33
MiCOM P441/P442 & P444 Page 109/220
The following table shows the relay menu for the fault locator, including the available setting
ranges and factory defaults:-
Menu text Default setting Setting range Step size
Min Max
GROUP 1
DISTANCE ELEMENTS
LINE SETTING
Line Length 1000 km
(625 miles) 0.3 km
(0.2 mile) 1000 km
(625 miles) 0.015 km
(0.005 mile)
Line Impedance
12 / In
Ω
0.001 / In
Ω
500 / In
Ω
0.001 / In
Ω
Line Angle 70° –90° +90° 0.1°
FAULT LOCATOR
kZm Mutual Comp 0 0 7 0.01
kZm Angle 0° 0° +360° 1°
4.1.1 Mutual Coupling
When applied to parallel circuits mutual flux coupling can alter the impedance seen by the
fault locator. The coupling will contain positive, negative and zero sequence components. In
practice the positive and negative sequence coupling is insignificant. The effect on the fault
locator of the zero sequence mutual coupling can be eliminated by using the mutual
compensation feature provided. This requires that the residual current on the parallel line is
measured, as shown in Appendix B. It is extremely important that the polarity of connection
for the mutual CT input is correct, as shown.
4.1.2 Setting Guidelines
The system assumed for the distance protection worked example will be used here, refer to
section 3.1. The Green Valley – Blue River line is considered.
Line length: 100Km
CT ratio: 1 200 / 5
VT ratio: 230 000 / 115
Line impedances: Z
1
= 0.089 + j0.476 = 0.484 / 79.4
° Ω
/km
ZM
0
= 0.107 + j0.571 = 0.581 / 79.4
° Ω
/km (Mutual)
Ratio of secondary to primary impedance =
1200 / 5
230000 / 115
= 0.12
Line Impedance = 100 x 0.484 / 79.4
°
x 0.12
= 5.81 / 79.4
° Ω
secondary.
Relay Line Angle settings 0
°
to 360
°
in 1
°
steps. Therefore, select Line Angle = 80
°
for
convenience.