2 Functions
194
7ST6 Manual
E50417-G1176-C251-A3
2.20
Command Processing
The SIPROTEC 4 7ST6 includes a command processing function for initiating switch-
ing operations in the system.
Control commands can originate from four command sources:
• Local operation using the keypad on the local user interface of the device
• Operation using DIGSI
• Remote operation using a substation automation and control system (e.g. SICAM)
• Automatic functions (e.g., using a binary input)
Switchgear with single and multiple busbars are supported. The number of switchgear
devices to be controlled is limited only by the number of binary inputs and outputs
present. High security against inadvertent device operations can be ensured if inter-
locking checks are enabled. A standard set of optional interlocking checks is provided
for each command issued to circuit breakers/switchgear.
2.20.1 Control Authorization
2.20.1.1 Command Types
Commands to the
Process
These are all commands that are directly output to the switchgear to change their
process state:
• Commands for the operation of circuit breakers (asynchronous; or synchronized by
applying the synchronism check and closing control function) as well as commands
for the control of isolators and earth switches.
Device-internal
Commands
These commands do not directly operate command outputs. They serve for initiating
internal functions, for communicating the detection of status changes to the device or
for acknowledging them.
• Manual override commands for „manual update“ of information on process-depen-
dent objects such as indications and switching states, e.g. if the communication with
the process is interrupted. Manually overridden objects are flagged as such in the
information status and can be displayed accordingly.
• Tagging commands are issued to „set“ the information values of internal objects,
such as switching authority (remote vs. local), parameter set changeover, data
transmission block to the SCADA interface, and measured value set-points.
• Acknowledgment and resetting commands for setting and resetting internal buffers
or data states.
• Information status commands to set/delete the additional „Information Status“ item
of a process object, such as
– Acquisition blocking,
– Output blocking.
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