ABB RELION RET670, Applications Manual

Page: 161 / 1016

To compensate for delta connected CTs, see equation 17 .
7. Enter the following values for the general settings of the differential protection
function, see table
22
Table 22: General settings of the differential protection function
Setting parameter Selected value for both Solution 1
(wye connected)
Selected value for both Solution 2
(delta connected)
RatedVoltageW1 110 kV 110 kV
RatedVoltageW2 36.75 kV 36.75 kV
RatedCurrentW1 165 A 165 A
RatedCurrentW2 495 A 495 A
ConnectTypeW1 WYE (Y) WYE (Y)
ConnectTypeW2 wye=y wye=y
ClockNumberW2 0 [0 deg] 0 [0 deg]
ZSCurrSubtrW1 On
Off 1)
ZSCurrSubtrW2 On
Off
1)
TconfigForW1 No No
TconfigForW2 No No
LocationOLT1 Winding 1 (W1) Winding 1 (W1)
LowTapPosOLTC1 1 1
RatedTapOLTC1 12 12
HighTapPsOLTC1 23 23
TapHighVoltTC1 23 23
StepSizeOLTC1 1.5% 1.5%
Other parameters Not relevant for this application.
Use default value.
Not relevant for this application.
Use default value.
1) Zero-sequence current is already removed by connecting main CTs in delta.
7.1.4.4 Summary and conclusions
SEMOD168160-5 v3
The IED can be used for differential protection of three-phase power transformers with
main CTs either wye or delta connected. However the IED has been designed with the
assumption that all main CTS are wye connected. The IED can be used in applications
where the main CTs are delta connected. For such applications the following shall be
kept in mind:
1MRK 504 163-UUS A
Section 7
Differential protection
Transformer protection RET670 2.2 ANSI 155
Application manual