2 Functions
150
7UT613/63x Manual
C53000-G1176-C160-2
2.4
Time Overcurrent Protection for Phase and Residual Currents
The overcurrent protection is used as backup protection for the short-circuit protection
of the main protected object and provides backup protection for external faults which
are not promptly disconnected and thus may endanger the protected object. It can
also be used as short-circuit protection for a further protected object if it has been as-
signed to corresponding measuring locations (see Subsection 2.1.4 in „Assignment of
Protection Functions to Measuring Locations/Sides“ under „Further 3-phase Protec-
tion Functions“) and these are fed into the correct current transformer sets.
Time overcurrent protection for phase currents takes its currents from the side or mea-
suring location to which it is assigned (address
420
). Time overcurrent protection for
residual current always uses the sum of the phase currents of that side or measuring
location to which it is assigned (address
422
). The side or measuring location for the
phase currents may be different from that of the residual current.
If the main protected object is
PROT. OBJECT
=
1ph Busbar
(address
105
), the time
overcurrent protection is ineffective.
The time overcurrent protection provides two definite time stages (DT) and one
inverse time stage (IT) for each the phase currents and the residual current. The latter
may operate according to an IEC or an ANSI curve, or to a user defined curve.
7UT613/63x has three overcurrent protection functions for phase and residual cur-
rents where each can be used independent of each other at different locations. They
can, e.g. be implemented independently on various sides of the main protection object
or three-phase measuring locations. Assigning the different protective functions to the
sides or one-phase measuring locations are according to Section „Assigning the pro-
tective functions to the measuring locations/sides “ is performed.
The pickup and trip messages of all levels, from all O/C phase functions are included
in the group indications
„Overcurrent PU“
and
„OvercurrentTRIP“
.
2.4.1
General
The time overcurrent protection provides two definite time stages and one inverse time
stage for each of the phase currents and the residual current. The latter may operate
according to an IEC or an ANSIuser requirements or a user defined characteristic.
2.4.1.1
Definite Time, Instantaneous Overcurrent Protection (UMZ)
The definite time stages (DT) for phase currents and the threefold zero sequence
current (sum of the phase currents) are also available when an inverse time charac-
teristic was configured in the definition of the scope of functions (address
120
/
130
/
132
and/or
122
/
134
/
136
).
Pickup, Tripping
Two definite time stages are available for each the phase currents and the zero se-
quence current. For the
I
>>-stages each phase current and the zero sequence current
are compared with the common pickup values
I>>
and
3I0>>
and are signalled when
exceeded. After the user-defined time delays
T I>>
or
T 3I0>>
have elapsed, trip
signals are issued that are also available for each stage. The reset value is approxi-
mately 95 % below the pickup value for settings above
I
N
. For lower values the dropout
ratio is reduced in order to avoid intermittent pickup on currents near the pickup value
(e.g. 90 % at 0.2 ·
I
N
).
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 ...
Page 519: ...A 2 Terminal Assignments 519 7UT613 63x Manual C53000 G1176 C160 2 7UT635 B ...
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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 ...