Siemens siprotec 7SJ63, Инструкция по эксплуатации

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Functions
6-74
7SJ63 Manual
C53000-G1140-C120-1
the voltage magnitudes of the other two phases are simultaneously above the setting
value entered at address
93+0$;
.
6.6.1.2 Current Elements
The current elements associated with sensitive ground fault detection typically operate
for low magnitudes of zero sequence current. They are typically applied in systems
where ground fault currents are limited by neutral resistors.
There are two current elements used for sensitive ground fault protection. A definite
time element similar to the 50N-2 or 67N-2 elements is used, as well as an element
that may be operated with either a fixed time delay (similar to the 50N-1 and 67N-1
elements) or with a user defined curve (similar to the 51N and 67N-TOC elements).
Each of the elements may be directional or non-directional.
6.6.1.3 Determination of Direction
Method of
Directional
Measurement The calculation algorithm filters the measured values so that it is highly accurate and
insensitive to higher harmonics (particularly the 3rd and 5th harmonics – which are of-
ten present in zero sequence currents).
Both the zero sequence or displacement voltage (V
0
or 3V
0
) and the zero sequence
current (3I
0
) are used to determine direction to a fault or grounded connection. Before
the determination of direction is initiated, the voltage element (and possibly the current
element) must be picked up and a programmable component of 3I
0
must exceed a
programmable setting (address
5(/($6(',5(&7
). The programmable com-
ponent of 3I
0
compared to address depends on the setting at address
0($60(7+2'
. Address establishes the directional measurement method that
will be used.
If address is set to
&263+,
, then the component of 3I
0
that is in phase with the
displacement voltage is compared to the setting at address . This current is des-
ignated 3I
0real
, and if larger than the setting at address , directional determination
is initiated. Once directional determination is initiated, the current 3I
0real
and the dis-
placement voltage V
0
(or 3V
0
) are used to calculate the real component of the zero
sequence power supplied to the fault. Both in a grounded system and in an unground-
ed system, a ground fault actually supplies zero sequence real power to the rest of the
system. Therefore, if the calculated zero sequence real power supplied to the fault is
negative (P
0
<0), the fault is considered in the direction of the protected equipment (for-
ward direction). If the calculated zero sequence real power supplied to the fault is pos-
itive (P
0
>0), then the fault is considered to be in the opposite direction (reverse direc-
tion). This method is typically used to determine the direction of high impedance faults
in a grounded system.
If address is set to
6,13+,
, then the component of 3I
0
that is 90° out of phase
with the displacement voltage is compared to the setting at address . This current
is designated 3I
0 reactive
, and if larger than the setting at address , directional de-
termination is initiated. Once directional determination is initiated, the current
3I
0reactive
and the displacement voltage V
0
(or 3V
0
) are used to calculate the reactive
component of the zero sequence power supplied to the fault. Both in a grounded sys-
tem and in an ungrounded system, a ground fault actually supplies zero sequence re-
active power to the rest of the system. Therefore, if the calculated zero sequence re-
active power supplied to the fault is negative (Q
0
<0), the fault is considered in the di-
rection of the protected equipment (forward direction). If the calculated zero sequence
reactive power supplied to the fault is positive (Q
0
>0), then the fault is considered to
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