Control Of Switchgear - Siemens siprotec 7SA522 User Manual

Control During Operation
7.4

Control of Switchgear

7-36
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A SIPROTEC 4 device 7SA522 contains control functions that allow for opening and
closing of power system switching devices (i.e. circuit breakers). Local control is pos-
sible utilizing different elements of the 7SA522. Breaker control from a remote location
is also possible using the SCADA interface or DIGSI
with a PC running DIGSI
mote" operation for breaker control purposes.) Some control actions from a 7SA522
include unsynchronized commands for circuit breakers, circuit switchers, ground
switches, etc., and stepping commands for increasing or decreasing transformer LTC
steps.
Safety mechanisms in the command path ensure a command can only take place if
the check of previously defined safety criteria is concluded positively.
If a power system switching device has auxiliary contacts that indicate the position of
the device and these contacts are connected to the 7SA522 and configured as double-
point indications then the switching device provides feedback indication that are mon-
itored for plausibility of control actions. If a switching device does not indicate either
the closed or open position, the display for the switching device indicates an unvalid
position in the 7SA522. All subsequent control operations to the equipment are inter-
locked.
Control from a 7SA522 to a power system equipment can originate from four sources:
− Local operation using the operator control panel,
− Binary inputs,
− Remote operation using the SCADA interface,
− Operation with a PC, via the operating interface and DIGSI
Switching priority for the four command sources is set using the Switching Authority.
For Interlocked Switching, all programmed interlocking conditions are checked before
a control operation is performed. If one of the conditions is not met, then the command
is rejected and an error message is recorded and displayed. Fixed, predefined, stan-
dard interlocking features are implemented in the 7SA522 and can be configured (ac-
tivated) for the specific application. The following tests can be activated (on) or deac-
tivated (off) for a switching device:
• Device Position (check SCHEDULED = ACTUAL comparison).
• Substation controller, to be implemented with Version 4.2,
• Zone controlled (Field interlocking e.g., logic in CFC),
• Blocking by protection (control operations blocked by protective functions),
• Double operation (blocking of multiple control operations),
• Switching authority (Local/Remote),
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4, connected to the front serial port, is considered a "re-
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4. (Performing control functions
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4.
7SA522 Manual
C53000-G1176-C119-2