GE P642 Technical Manual page 150

Chapter 6 - Transformer Differential Protection
Setting in GROUP 1 SYSTEM CONFIG
HV Connection
HV Grounding
HV Nominal
HV Rating
% Reactance
LV Vector Group
LV Connection
LV Grounding
LV Nominal
LV rating
TV Vector Group
TV Connection
TV Grounding
TV Nominal
TV rating
Phase Sequence
VT Reversal
CT1 Reversal
CT2 Reversal
Vector correction and zero sequence filtering are automatically performed by virtue of the LV Vector Group setting
and the HV Grounding and LV Grounding settings.
The device calculates the ratio correction factors as follows:
I
nom T CT
K
=
amp T CT , 1
S
3 V
I
nom T CT
K
=
amp T CT , 5
S
3 V
I
nom T CT
K
=
amp T CT , 3
S
3 V
where:
Sref = common reference power for all ends
●
K
●
amp, T1CT, T2CT, T3CT
I
nom, T1CT, T2CT, T3CT
V = primary nominal voltage of HV, LV, or TV windings
●
nom, HV, LV, TV
126
800
, 1
=
6
175 10
×
ref
3 218 5 10 .
× ×
nom HV ,
1200
, 5
=
6
175 10
×
ref
3 115 10
× ×
nom LV ,
2000
, 3
=
6
175 10
×
ref
3 13 8 10 .
× ×
nom TV ,
= ratio correction factor of T1 CT, T2 CT, or T3 windings
= primary nominal currents of the main current transformers
Y-Wye
Grounded
218.50 kV
175.00 MVA
10.00%
0
Y-Wye
Grounded
115.00 kV
145.00 MVA
1
D-Delta
Grounded
13.800 kV
30.00 MVA
Standard ABC
No Swap
No Swap
No Swap
1 73 . 0 0
=
3
1 3 . 6 6 6
=
3
= . . 273 0
3
Value
P64x-TM-EN-1.3
P64x