Siemens siprotec 7SA6, Manual

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Functions
6-311
7SA6 Manual
C53000-G1176-C156-2
•
|cos
ϕ
|<: untershooting a preset magnitude of the power factor.
Metering of Energy
The 7SA522 integrates the calculated power which is then made available with the
“Measured Values”. The components are listed in table 6-10. The signs (positive = ex-
port, negative = import) are defined the same as for the powers.
Please take into consideration that 7SA6 is, above all, a protection device. The accu-
racy of the measured values depends on the current transformer (normally protection
core) and the tolerances of the device. The metering is therefore not suited for tarif
purposes. The counters can be reset to zero or any initial value (see Subsubsection
7.1.3.3).
6.23.3 Data Storage for Fault Recording
The Distance Protection 7SA6 has a fault recording memory. The instantaneous val-
ues of the measured signals
i
L1
, i
L2
, i
L3
, i
E
or i
EE
, and u
L1
, u
L2
, u
L3
, u
en
(voltages according to type of connection) are sampled at an interval of 1 ms (at
50 Hz) respectively 0.83 ms (at 60 Hz), and stored in a circular shift register (20 sam-
ples per cycle). In the event of a fault the data is memorized for a selectable period of
time, not exceeding 5 s per fault. In a total period of approx. 15 s up to 8 fault record-
ings can be memorized. The recording memory is automatically updated in the event
of a new system fault, thereby not requiring an acknowledgment. In addition to storage
of the fault recording by the protection fault detection, a recording may also be initiated
via binary input, the integrated keypad and display, or via the serial PC or service in-
terface.
The data can be retrieved via the serial interfaces by means of a personal computer
and evaluated with the protection data processing program DIGSI
®
4 and the graphic
analysis software SIGRA 4. The latter graphically represents the data recorded during
the system fault and calculates additional information such as the impedance or RMS
values from the measured values. A selection may be made as to whether the currents
and voltages are represented as primary or secondary values. Binary signal traces
(marks) of particular events e.g. “fault detection”, “tripping” are also represented.
If the device has a serial system interface, the fault recording data can be passed on
to a central device via this interface. The evaluation of the data is done by applicable
programs in the central device. Currents and voltages are referred to their maximum
values, scaled to their rated values and prepared for graphic representation. In addi-
tion, internal events are recorded as binary traces (marks), e.g. “fault detection”, “trip-
ping”.
Table 6-19 Operational Metering Impulse Counters
Measured Values primary
W
p
+ active power, export kWh, MWh, GWh
W
p
– active power, import kWh, MWh, GWh
W
q
+ reactive power, export kVARh, MVARh, GVARh
W
q
– reactive power, import kVARh, MVARh, GVARh