Example - GE L90 Instruction Manual

10.9 PHASE DISTANCE THROUGH POWER TRANSFORMERS
d) ZONE 1 SETTING IN APPLICATION (B)
As the transformer is not located between the potential source and the reach point for Z1, the reach impedance must not
include the positive-sequence impedance of the transformer. The CTs are located on the other side of the transformer, thus
transformer ratio must be included:
e) ZONE 4 SETTING IN APPLICATION (B)
As the transformer is located between the potential source and the reach point for , the reach impedance must include the
positive-sequence impedance of the transformer. The VTs are located on the other side of the transformer, thus transformer
ratio must be included:
Given the following for the system shown in the previous section:
= 30  85° (intended reach of Zone 1)
Z
X
= 0.06  88° (intended reach of Zone )
Z
H
n = 8000:5 = 1600 (located at H)
CT
n = 315000:120 = 2625 (located at X)
VT
Transformer: 13.8/315 kV, 150 MVA, 10%, delta/wye, 315 kV side lagging 30°
Transformer impedance:
The Zone 1 settings are:
PHS DIST Z1 REACH:
PHS DIST Z1 RCA:
PHS DIST Z1 XMFR VOL CONNECTION:
PHS DIST Z1 XMFR CUR CONNECTION:
The settings are:
PHS DIST REACH:
PHS DIST RCA:
PHS DIST XMFR VOL CONNECTION:
PHS DIST XMFR CUR CONNECTION:
10
10-28
Z
1
10
 
--------- -
Z at H
T
100
13.8
 ---------- -
Z 30
1
315
"0.80"
"85"
"None"
"Dy1"
"2.60"
"89"
"Yd11"
"None"
L90 Line Current Differential System
V n
 
H CT
 
------ - ---------
Z
 
X
V n
X VT
2
 
13.8
 
------------------ -
0.127 90
150
1600
 ------------ - 
0.8011 85
2625
10 APPLICATION OF SETTINGS
(EQ 10.22)

10.9.2 EXAMPLE

(EQ 10.23)
(EQ 10.24)
GE Multilin