GE UR Series L90, Instruction Manual, Page: 632 / 846

10-28 L90 Line Current Differential System GE Multilin
10.9 PHASE DISTANCE THROUGH POWER TRANSFORMERS 10 APPLICATION OF SETTINGS
10
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:
(EQ 10.22)
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:
10.9.2 EXAMPLE
Given the following for the system shown in the previous section:
Z
X
= 30
 
85° (intended reach of Zone 1)
Z
H
= 0.06
 
88° (intended reach of Zone )
n
CT
= 8000:5 = 1600 (located at H)
n
VT
= 315000:120 = 2625 (located at X)
Transformer: 13.8/315 kV, 150 MVA, 10%, delta/wye, 315 kV side lagging 30°
Transformer impedance:
(EQ 10.23)
The Zone 1 settings are:
(EQ 10.24)
PHS DIST Z1 REACH:
"0.80"
PHS DIST Z1 RCA:
"85"
PHS DIST Z1 XMFR VOL CONNECTION:
"None"
PHS DIST Z1 XMFR CUR CONNECTION:
"Dy1"
The settings are:
PHS DIST REACH:
"2.60"
PHS DIST RCA:
"89"
PHS DIST XMFR VOL CONNECTION:
"Yd11"
PHS DIST XMFR CUR CONNECTION:
"None"
Z
1
Z
X
V
H
V
X
-------
 
 
n
CT
n
VT
---------
 
Z
T
at H
 
10
100
----------
13.8
 
2
150
-------------------

0.127

90
 
Z
1
30
13.8
315
-----------

1600
2625
-------------

0.8011

85
 