Example - GE G60 Instruction Manual

CHAPTER 8: APPLICATION OF SETTINGS
8.3.1.4 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:
8.3.1.5 Zone 3 setting in application B
As the transformer is located between the potential source and the reach point for Zone 3, 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:

8.3.2 Example

Given the following for the system shown in the previous section:
Z = 30 Ω ∠85° (intended reach of Zone 1)
X
= 0.06 Ω ∠88° (intended reach of Zone 3)
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:
: "0.80"
PHS DIST Z1 REACH
: "85"
PHS DIST Z1 RCA
PHS DIST Z1 XMFR VOL CONNECTION
PHS DIST Z1 XMFR CUR CONNECTION
The Zone 3 settings are:
: "2.60"
PHS DIST Z3 REACH
: "89"
PHS DIST Z3 RCA
PHS DIST Z3 XMFR VOL CONNECTION
PHS DIST Z3 XMFR CUR CONNECTION
G60 GENERATOR PROTECTION SYSTEM – INSTRUCTION MANUAL
: "None"
: "Dy1"
: "Yd11"
: "None"
PHASE DISTANCE THROUGH POWER TRANSFORMERS
Eq. 8-37
Eq. 8-38
Eq. 8-39
Eq. 8-40
8
Eq. 8-41
8-17