Siemens siprotec 7SD5, Руководство пользователя

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2.1 General
49
7SD5 Manual
C53000-G1176-C169-1
Example:
Phase current transformers 500 A / 5 A
Earth current transformer 60 A / 1 A
• Connection of the
I
4
input to the earth current of the parallel line (for parallel line
compensation of the distance protection and/or fault location):
Address
220
is then set to:
I4 transformer
=
In paral. line
and usually
address
221 I4/Iph CT
= 1.
If the set of current transformers on the parallel line however has a different trans-
formation ratio to those on the protected line, this must be taken into account in
address
221
:
Address
220
is then set to:
I4 transformer
=
In paral. line
and address
221 I4/Iph CT
= I
N paral. line
/ I
N prot. line
Example:
Current transformers on protected line 1200 A
Current transformers on parallel line 1500 A
• Connection of the
I
4
input to the starpoint current of a transformer; this connection
is occasionally used for the polarisation of the directional earth fault protection:
Address
220
is then set to:
I4 transformer
=
IY starpoint
, and address
221
I4/Iph CT
is according to transformation ratio of the starpoint transformer to the
transformer set of the protected line.
• If the input
I
4
is not required, set:
Address
220 I4 transformer
=
Not connected
,
Address 221 I4/Iph CT is then irrelevant.
In this case, the neutral current is calculated from the sum of the phase currents.
Nominal Frequency The nominal frequency of the system is set in address
230 Rated Frequency
. The
presetting according to the ordering code (MLFB) only needs to be changed if the
device is applied in a region different to the one indicated when ordering. You can set
50 Hz
or
60 Hz
.
System Starpoint If the distance protection has been configured as the main protection function or in
combination with differential protection, the manner in which the system starpoint is
earthed must be considered for the correct processing of earth faults and double earth
faults. Accordingly, set for address
207 SystemStarpoint
=
Solid Earthed
,
Peterson-Coil
or
Isolated
. For „low-resistant“ earthed systems set
Solid
Earthed
.
Distance Unit Address
236 Distance Unit
determines the distance unit (
km
or
Miles
) for the
fault location indications. If the compounding function of the voltage protection is used,
the overall line capacitance is calculated from the line length and the capacitance per
unit length. If compounding is not used and fault location is not available, this param-
eter is of no consequence. Changing the distance unit will not result in an automatic
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