SERVICE MANUAL R5888B
QUADRAMHO Chapter 1
Page 21 of 27
19.13 Worked example No. 2
To set distance protection at one end of 60 km double circuit 132kV line on steel
towers for use in a directional comparison blocking scheme.
19.14 Data
Line to be protected: 60km, 132kV double circuit between FEB 132 and March
132 (settings for FEB relay only) using Quadramho Type A.
Line data:
Positive sequence series impedance = Z
1
= 0.44 /69° ohms/km
= (0.16 + j0.41) ohm/km
Zero sequence series impedence = Z
0
= 1.09 /72° ohms/km
= (0.34 + j1.03) ohms/km
VT ratio = 132000/110V
CT ratio = 500/1A
Source data:
JAN 132 – min source impedance = 3.48
/88°
max source impedance = 24.9 /88°
Z
S0
/Z
S1
= 1.0 /0°
AUG 132 – source impedance = 34.8
/88°
Z
S0
/Z
S1
= 1.0 /0°
19.15 Selecting Zone 1 reach
Required Zone 1 reach is to be 80% of FEB – MARCH line impedance
Ratio of secondary impedance to primary impedance
=
110
x
500
= 0.417
1 132 x 10
3
Required Zone 1 reach
= 0.8 x 60 x 0.44
/69° ohms primary
= 21.1
/69° ohms primary
= 8.8
/69° ohms secondary
Jan 132
20km
500MVA
equivalent
source
R
max 5000MVA
min 700MVA
equivalent
source
60km 40km
Feb 132 March 132 Aug 132
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