are rotated by 30° in clockwise direction. Thus the DAC delta CT connection must be
used for 69 kV CTs in order to put 69 kV & 12.5 kV currents in phase.
T
o ensure proper application of the IED for this power transformer it is necessary to do
the following:
1. Check that HV & LV CTs are connected to 5 A CT inputs in the IED.
2. For second solution make sure that HV delta connected CTs are DAC connected.
3. For wye connected CTs make sure how they are stared (that is, grounded) to/from
protected transformer.
4. Enter the following settings for all three CT input channels used for the LV side CTs
see table
15.
Table 15: CT input channels used for the LV side CTs
Setting parameter Selected value for both solutions
CTprim 800
CTsec 5
CT_WyePoint ToObject
5. Enter the following settings for all three CT input channels used for the HV side
CT
s, see table
16.
Table 16: CT input channels used for the HV side CTs
Setting parameter Selected value for solution 1 (wye
connected CT)
Selected value for solution 2 (delta
connected CT)
CTprim 300
EQUATION1888 V1 EN-US (Equation 14)
CTsec 5 5
CT_WyePoint From Object ToObject
To compensate for delta connected CTs, see equation 14.
6. Enter the following values for the general settings of the Transformer dif
ferential
protection function, see table
17.
1MRK 502 071-UUS A Section 7
Differential protection
Generator protection REG670 2.2 ANSI and Injection equipment REX060, REX061, REX062 147
Application manual
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