2 Functions
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7UT613/63x Manual
C53000-G1176-C160-2
Figure 2-41
Definition of current direction at busbar with 4 feeders
The differential protection feature of the 7UT613/63x refers all currents to the rated
current of the protected object. The device is informed during setting about the rated
current of the protected object (in this case the busbar or line), and about the primary
rated CT currents. Measured value matching is therefore reduced to magnitude fac-
tors. The basis for current comparison is the rated busbar current (address
371
I
PRIMARY OP.
). If the feeders or ends have different rated currents, the largest of the
three rated currents is used as the basis for the current comparison, and all other cur-
rents are converted accordingly. As a rule, no external matching devices are neces-
sary.
Differential Current
Monitoring
Whereas a high sensitivity of the differential protection is normally required for trans-
formers, reactors, and rotating machines in order to detect even small fault currents,
high fault currents are expected in case of faults on a busbar or a short line so that a
higher pickup threshold (above rated current) is conceded here. This allows for a con-
tinuous monitoring of the differential currents on a low level. A small differential current
in the range of operational currents indicates a fault in the secondary circuit of the
current transformers.
This monitor operates phase-selectively. When, during normal load conditions, a dif-
ferential current is detected in the order of the load current of a feeder, this indicates
a missing secondary current, i.e. a fault in the secondary current leads (short-circuit or
open-circuit). This condition is annunciated with time delay. The differential protection
is blocked in the associated phase at the same time.
Feeder Current
Guard
With busbars and short lines, a release of the trip command can be set if a threshold
is exceeded by one of the incoming currents. The three phase currents at each mea-
suring location of the protected object are monitored for over-shooting of a set value.
Trip command is allowed only when at least one of these currents exceeds a certain
(settable) threshold.
2.2.6
Single-phase Differential Protection for Busbars
7UT613/63x Depending on the ordered model, it provides 9 or 12 current inputs of
equal design. This allows for a single-phase differential current busbar protection for
up to 9 or 12 feeders.
There are two connection possibilities:
• One 7UT613/63x is used for each phase. Each phase of all busbar feeders is con-
nected to one phase dedicated device 7UT613/63x.
• The three phase currents of each feeder are summarised into a single-phase sum-
mation current. These currents are fed to one device per feeder.
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 ...