Functions
2.9 Backup Time Overcurrent Protection
SIPROTEC, 7SD610, Manual
C53000-G1176-C145-6, Release date 02.2011
119
The above example shows that the maximum expected operating current may directly be applied as setting
here.
Primary: Set value
I
P = 630 A,
Secondary: Setting value
I
P = 5.25 A, i.e. (630 A/600 A) X 5 A.
The set time multiplier
Time Dial TD Ip
(address
2643
) or
D Ip Dir.
(address
2691
) results from the
grading coordination chart defined for the network. For the use as emergency overcurrent protection, shorter
delay times make sense (one grading time step above instantaneous tripping), since this function is to work
only in case of an interruption of the data communication for the differential protection.
The time multiplier
TimeDial TD3I0p
(address
2653
) or
D 3I0p Dir.
(address
2696
), can normally be set
shorter, according to a separate time grading schedule for ground currents. If only the phase currents are to be
monitored, set the pickup value of the residual current stage to
∞
.
In addition to the current-dependent delays, a time fixed delay can be set, if necessary. The setting
T Ip Add
(address
2646
) or
T Ip Add Dir.
(address
2692
) for phase currents and
T 3I0p Add
(address
2656
)
or
T 3I0p Add Dir.
(address
2697
) for earth currents add to the times of the set characteristics.
The parameter
I(3I0)p Tele/BI
(address
2670
) or
IPDir.Telep/BI
(address
2698
) determines wheth-
er, via the binary input
„>O/C InstTRIP“
(No 7110), the delay
T Ip Time Dial
(address
2642
) or
T Ip
Dir.
(address
2690
) including additional delay
T Ip Add
(address
2646
) or
T Ip Add Dir.
(address
2692
)
and
T 3I0p TimeDial
(address
2652
) or
T 3I0p Dir.
(address
2695
) including additional delay
T 3I0p
Add
(address
2656
) or
T 3I0p Add Dir.
(address
2697
) can be bypassed. The binary input (if allocated)
is applied to all stages of the time-overcurrent protection. With
I(3I0)p Tele/BI
=
YES
or
IPDir.Telep/BI
=
YES
you define that the
I
P>stages trip without delay after pickup if the binary input was
activated. For
I(3I0)p Tele/BI
=
NO
or
IPDir.Telep/BI
=
NO
, the set delays are always active.
Instantaneous tripping by the operational auto-reclosure function should only be chosen if the overcurrent pro-
tection is set to emergency function. Since the differential protection guarantees a fast and selective tripping
with or without auto-reclosure, the overcurrent protection as a backup protection may not perform a non-selec-
tive trip, even before auto-reclosure.
If the
I
P stage, when switching the line onto a fault, is to re-trip without delay or with a short delay
SOTF Time
DELAY
(address
2602
, see above under margin heading „General“), the parameter
I(3I0)p SOTF
(address
2671
) or
IP Dir. SOTF
(address
2699
) is set to
YES
. We recommend, however, not to choose the sensitive
setting for the fast tripping as switching onto a fault could cause a solid short circuit. It is important to avoid that
the selected stage picks up due to transients during line energization.
Additional Stage
I
ph
>>>
The
I
>>> stage can be used as an additional definite-time overcurrent stage since it operates independently of
the other stages In this case, the enable input
„>I-STUB ENABLE“
(no. 7131) must be activated permanently
(via a binary input or CFC).
Since the
I
>>> stage has an additional enable input, it is also suitable e.g. as an emergency stage if the re-
maining stages are used as backup stages. The enable input
„>I-STUB ENABLE“
(no. 7131) is then assigned
the output signal
„Emer. mode“
(no. 2054) - either via binary outputs and inputs or via the user-definable CFC
logic functions.
The considerations for the use of the I>>> stage as an emergency function are the same as for the I> stages.
The setting value
Iph> STUB
(address
2630
) must here, too, be higher than the maximum operational current
to be expected, in order to avoid pickup without fault. The delay T
T Iph STUB
(address
2631
), however, can
be shorter than defined in the time grading schedule, since this stage works only in emergency operation, i.e.
in case of a communication failure of the differential protection. Normally, one grading time above the base time
of the differential protection is sufficient.
Содержание SIPROTEC 7SD610
Страница 16: ...Contents SIPROTEC 7SD610 Manual C53000 G1176 C145 6 Release date 02 2011 16 ...
Страница 267: ...Functions 2 18 Command Processing SIPROTEC 7SD610 Manual C53000 G1176 C145 6 Release date 02 2011 267 ...
Страница 268: ...Functions 2 18 Command Processing SIPROTEC 7SD610 Manual C53000 G1176 C145 6 Release date 02 2011 268 ...
Страница 428: ...Appendix A 10 Measured Values SIPROTEC 7SD610 Manual C53000 G1176 C145 6 Release date 02 2011 428 ...
Страница 430: ...Literature SIPROTEC 7SD610 Manual C53000 G1176 C145 6 Release date 02 2011 430 ...
Страница 442: ...Glossary SIPROTEC 7SD610 Manual C53000 G1176 C145 6 Release date 02 2011 442 ...
Страница 448: ...Index SIPROTEC 7SD610 Manual C53000 G1176 C145 6 Release date 02 2011 448 ...
