2 Functions
126
7UT613/63x Manual
C53000-G1176-C160-2
Figure 2-43
Busbar protection with connection via summation current transformers (SCT)
Different schemes are possible for the connection of the current transformers. The
same CT connection method must be used for all feeders of a busbar.
The scheme as illustrated in figure 2-44 is the most commonly used. The three input
windings of the summation transformer are connected to the CT currents
I
L1
,
I
L3
and
I
E
. This connection is suitable for all kinds of systems regardless of the conditioning of
the system neutral. It is characterised by an increased sensitivity for earth faults.
Figure 2-44
Summation Transformer Connection L1-L3-E
For a symmetrical three-phase current (where the earth residual component
I
E
= 0)
the single-phase summation current is W =
√
3 times the winding unit value, as shown
in figure 2-45, i.e. the summation flux (ampere turns) is the same as it would be for
single-phase current
√
3 times the value flowing through the winding with the least
number of turns (ratio 1). For three-phase symmetrical fault currents equal to rated
current 1 x
I
N
, the secondary single-phase current is
I
M
= 100 mA. All relay character-
istic operating values are based on this type of fault and this current.
Summary of Contents for SIPROTEC 7UT613 series
Page 16: ...Contents 16 7UT613 63x Manual C53000 G1176 C160 2 Literature 631 Glossary 623 Index 633 ...
Page 30: ...1 Introduction 30 7UT613 63x Manual C53000 G1176 C160 2 ...
Page 506: ...A Appendix 506 7UT613 63x Manual C53000 G1176 C160 2 7UT633 D E ...
Page 508: ...A Appendix 508 7UT613 63x Manual C53000 G1176 C160 2 7UT633 P Q ...
Page 510: ...A Appendix 510 7UT613 63x Manual C53000 G1176 C160 2 7UT635 D E ...
Page 512: ...A Appendix 512 7UT613 63x Manual C53000 G1176 C160 2 7UT635 P Q ...
Page 515: ...A 2 Terminal Assignments 515 7UT613 63x Manual C53000 G1176 C160 2 7UT633 B ...
Page 517: ...A 2 Terminal Assignments 517 7UT613 63x Manual C53000 G1176 C160 2 7UT633 N ...
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Page 622: ...A Appendix 622 7UT613 63x Manual C53000 G1176 C160 2 ...
Page 632: ...Literature 632 7UT613 63x Manual C53000 G1176 C160 2 ...