ABB RELION 670 Series Applications Manual page 118

Section 6
Differential protection
CT input channels used for the LV side CTs
Setting parameter
CTprim
CTsec
CTStarPoint
To compensate for delta connected CTs, see equation 16.
6. Assume GBASVAL:1 is used for winding 1 (W1, HV-side) base values: Set Ibase = 301 A (rated
current), Ubase= 115 kV (rated voltage).
7. Assume GBASVAL:2 is used for winding 2 (W2, LV-side) base values: Set Ibase = 1391 A (rated
current), Ubase= 24.9 kV (rated voltage).
8. Enter the following values for the general settings of the differential protection function,
see table16.
Table 16:
Setting parameter
GlobalBaseSelW1
GlobalBaseSelW2
ConnectTypeW1
ConnectTypeW2
ClockNumberW2
ZSCurrSubtrW1
ZSCurrSubtrW2
TconfigForW1
TconfigForW2
LocationOLTC1
Other parameters
1)
To compensate for delta connected CTs.
2)
Zero-sequence current is already removed by connecting main CTs in delta.
Star-star connected power transformer with load tap changer and tertiary not loaded
delta winding
Single line diagrams for two possible solutions for such type of power transformer with all
relevant application data are given in figure 37. It shall be noted that this example is applicable
for protection of autotransformer with not loaded tertiary delta winding as well.
112
Selected value for Solution 1
(star connected CT)
1500
5
ToObject
General settings of the differential protection
selected value for both
Solution 1 (star conected CT)
1 (GBASVAL:1)
2 (GBASVAL:2)
Delta (D)
star=y
1 [30 deg lag]
Off
On
No
No
Not Used
Not relevant for this
application. Use default value.
1MRK 504 152-UEN B
Selected value for Solution 2 (delta
connected CT)
1500
=
866
3
EQUATION1889 V1 EN-US
5
ToObject
Selected value for both Solution 2 (delta
connected CT)
1 (GBASVAL:1)
2 (GBASVAL:2)
1)
STAR (Y)
star=y
1)
0 [0 deg]
Off
2)
On
No
No
Not Used
Not relevant for this application. Use
default value.
Application manual
(Equation 16)
SEMOD167854-305 v3