
2 Functions
102
7SD5 Manual
C53000-G1176-C169-1
With more than two line ends the parameter of address
1114
Tot.Line Length
is
to be considered. If the unit of length in address
236
is changed for the total line length
in address
1114
, the line data have to be set anew for the unit of length which has been
changed. It is possible to enter here unrealistic data (very long line with extremely high
capacitance). The charging current compensation is in that case ineffective and pro-
vides restraint with a very high restraint current. This can also be seen from the mea-
sured restraint values and from the output of an „effective-OFF“ indication.
In address
1221
Ic-comp.
you can determine whether the charging current compen-
sation is to be switched
ON
or
OFF
. Please note that the parameter
I-DIFF>
in
address
1210
must absolutely be increased to a value of 2 to 3 times
I
cN
before the
compensation is switched
OFF
, because otherwise a spurious trip might be the result.
Note
If the protected line section includes transformers or compensation reactors, the
charging current compensation must not be switched on.
In the following cases, an active protection device is not able to assess the charging
current (charging current compensation is ineffective):
• No voltage measurement (depends on configuration),
• Fuse Failure, or
• Detection of a
Σ
U measuring error.
In all these cases the protection device remains active for its assigned line section, but
must return to its "classic" restraint strategy, i.e. with
I
cRest
being 2 to 3 times
I
cN
. The
calculated charging current is set to zero. The charging current tolerance, however,
should be set to 2.5 ·
I
cN
· line section portion to avoid spurious tripping of the protec-
tion. Address
1224
IcSTAB/IcN
allows you to determine the charging current re-
straint factor. Since in the latter descriptions the charging current was already consid-
ered using setting
1210
I-DIFF>
= 1 ·
I
cN
, the additional restraint value of the device
is calculated as follows: (
IcSTAB/IcN
– 1) ·
I-DIFF>
divided by the number of de-
vices. This value is added to the normal restraint in case of a failure of the the protec-
tive device voltage to be measured.
Inrush Restraint
The inrush restraint of the differential protection is only necessary when the devices
are operated on a transformer or on lines which end on transformers. The transformer
is inside the differential protection zone. At address
2301
INRUSH REST.
it can be
switched
ON
or
OFF
.
It is based on the evaluation of the second harmonic which exists in the inrush current.
Ex-works a ratio of
15 %
of the
2nd HARMONIC
I
2fN
/
I
fN
is set under address
2302
,
which can normally be taken over. However the component required for restraint can
be parameterized. In order to be able to achieve a higher degree of restraint in case
of exceptionally unfavourable inrush conditions, you may also set a smaller value.
However, if the local measured current exceeds a value set in address
2305
MAX
INRUSH PEAK
, there will be no inrush restraint. The peak value is decisive. The set
value should be higher than the maximum inrush current peak value that can be ex-
pected. For transformers set the value above
√
2·
I
NTransf.
/u
kTransf.
. If a line ends on a
transformer, a smaller value may be selected, considering the damping of the current
by the line impedance.
The crossblock function can be activated (
YES
or deactivated (
NO
) in address
2303
CROSS BLOCK
. The time after exceeding of the current threshold for which this cross-
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Содержание siprotec 7SD5
Страница 2: ...2 7SD5 Manual C53000 G1176 C169 1 w w w E l e c t r i c a l P a r t M a n u a l s c o m ...
Страница 4: ...4 7SD5 Manual C53000 G1176 C169 1 w w w E l e c t r i c a l P a r t M a n u a l s c o m ...
Страница 18: ...Contents 18 7SD5 Manual C53000 G1176 C169 1 w w w E l e c t r i c a l P a r t M a n u a l s c o m ...
Страница 34: ...1 Introduction 34 7SD5 Manual C53000 G1176 C169 1 w w w E l e c t r i c a l P a r t M a n u a l s c o m ...
Страница 444: ...2 Functions 444 7SD5 Manual C53000 G1176 C169 1 w w w E l e c t r i c a l P a r t M a n u a l s c o m ...
Страница 580: ...4 Technical Data 580 7SD5 Manual C53000 G1176 C169 1 w w w E l e c t r i c a l P a r t M a n u a l s c o m ...
Страница 682: ...Literature 682 7SD5 Manual C53000 G1176 C169 1 w w w E l e c t r i c a l P a r t M a n u a l s c o m ...
Страница 698: ...Index 698 7SD5 Manual C53000 G1176 C169 1 w w w E l e c t r i c a l P a r t M a n u a l s c o m ...