Siemens siprotec 7SA522, User Manual

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Introduction
1-2
7SA522 Manual
C53000-G1176-C119-2
1.1 Overall Operation
The numerical Distance Protection SIPROTEC
®
7SA522 is equipped with a powerful
32 Bit microprocessor. This provides fully numerical processing of all functions in the
device, from the acquisition of the measured values up to the output of commands to
the circuit breakers. Figure 1-1 shows the basic configuration of the device.
Analog Inputs The measuring inputs MI transform the currents and voltages derived from the instru-
ment transformers and match them to the internal signal levels for processing in the
device. The device has 4 current and 4 voltage inputs. Three current inputs are pro-
vided for measurement of the phase currents, a further measuring input (I
4
) may be
configured to measure the earth current (residual current from the current transformer
star-point), the earth current of a parallel line (for parallel line compensation) or the
star-point current of a power transformer (for earth fault direction determination). A
voltage measuring input is provided for each phase–earth voltage. A further voltage
input (U
4
) may optionally be used to measure either the displacement voltage (e–n–
voltage) or any other voltage U
X
(for overvoltage protection). The analogue signals are
then routed to the input amplifier group IA.
µC
∩
#
ERROR
RUN
Output Relays
user-
programmable
LEDs
on the front
panel, user-
programmable
Display on
the Front Panel
Front Serial Oper-
ating Interface
to
PC
Time
Synchronization
radio
clock
I
L1
I
L2
I
L3
I
4
U
L1
U
L2
U
L3
U
4
7 8 9
4 5 6
1 2 3
.
0 +/-
(6& (17(5
Operator
control panel
U
aux
Binary inputs, programmable
Power supply
Rear Serial
Service Interface
MI IA AD µC OA
Figure 1-1 Hardware structure of the numerical device 7SA522 (maximum configuration)
Serial
System Interface
to
SCADA
PC/
modem