Example 3: Autotransformer With Unloaded Delta Winding - GE P642 Technical Manual

P64x
These matching factors are also displayed in the SYSTEM CONFIG column (Match Factor CT1 and Match Factor
CT2)
Now set the current differential parameters as follows:
Setting in GROUP 1 DIFF PROTECTION
Trans Diff
Set Mode
Is1
K1
Is2
K2
tdiff
Is-CTS
Is-HS1
HS2 Status
Zero seq filt HV
Zero seq filt LV
Zero seq filt TV
IH2 Diff Block
IH2 Diff Set
Cross Blocking
CT Saturation
No Gap
IH5 Diff Block
IH5 Diff Set
Circuitry Fail
5.4

EXAMPLE 3: AUTOTRANSFORMER WITH UNLOADED DELTA WINDING

Consider an autotransformer with the following specifications:
● Power rating: 175/175/30 MVA
Connection type: YNyn0d1
●
Voltage specification: 230/115/13.8 kV.
●
● HV CT ratio: 1200:5
LV CT ratio: 1200:5
●
● Neutral CT ratio: 1200:5
HV taps at +5% and -15%
●
The winding configuration is set to HV + LV + TV. The CT on the HV line side is connected to T1 CT, the CT on the HV
neutral side is connected to T2 CT, and the CT on the LV side is connected to T3 CT.
P64x-TM-EN-1.3
Chapter 6 - Transformer Differential Protection
Enabled
Advance
200.0e-3 PU
30.00%
1.000 PU
80.00%
0 s
1.500 PU
10.00 PU
Disabled
Enabled
Enabled
Enabled
Enabled
20%
Enabled
Enabled
Enabled
Enabled
35%
Disabled
Value
127