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Functions
2.21 Command Processing
2.21.4
Interlocking
System interlocking is executed by the user-defined logic (CFC).
2.21.4.1 Description
Interlocking checks in a SICAM / SIPROTEC 4 system are normally divided in the following groups:
• System interlocking relies on the system data base in the substation or central control system.
• Bay interlocking relies on the object data base (feedbacks) of the bay unit.
• Cross-bay interlocking via GOOSE messages directly between bay units and protection relays (inter-relay
communication with GOOSE is accomplished via the EN100 module).
The extent of the interlocking checks is determined by the configuration of the relay. To obtain more information
about GOOSE, please refer to the SIPROTEC 4 System Description /1/.
Switching objects that require system interlocking in a central control system are assigned to a specific param-
eter inside the bay unit (via configuration matrix).
For all commands, operation with interlocking (normal mode) or without interlocking (Interlocking OFF) can be
selected:
• For local commands by reprogramming the settings with password prompt
• For automatic commands, via command processing. by CFC and deactivated interlocking recognition,
• For local / remote commands, using an additional interlocking disable command, via Profibus.
Interlocked / Non-Interlocked Switching
The configurable command checks in the SIPROTEC 4 devices are also called "standard interlocking". These
checks can be activated via DIGSI (interlocked switching/tagging) or deactivated (non-interlocked).
Deactivated interlock switching means the configured interlocking conditions are not checked in the relay.
Interlocked switching means that all configured interlocking conditions are checked within the command pro-
cessing. If a condition is not fulfilled, the command will be rejected by a message with a minus added to it (e.g.
"„CO–""), immediately followed by a message.
The following table shows the possible types of commands in a switching device and their corresponding an-
nunciations. For the device the messages designated with *) are displayed in the event logs, for DIGSI they
appear in spontaneous messages.
Control issued
Manual tagging (positive / negative)
Information state command, input blocking
Information state command, output blocking
Cancel command
The "plus" appearing in the message is a confirmation of the command execution. The command execution
was as expected, in other words positive. The minus sign means a negative confirmation, the command was
rejected. Possible command feedbacks and their causes are dealt with in the SIPROTEC 4 System Descrip-
tion. The following figure shows operational indications relating to command execution and operation response
information for successful switching of the circuit breaker.
The check of interlocking can be programmed separately for all switching devices and tags that were set with
a tagging command. Other internal commands such as manual entry or abort are not checked, i.e. carried out
independent of the interlocking.
290
Type of Command
Command
Switching
CO
Manual tagging
MT
Input blocking
ST
Output blocking
ST
Cancel
CA
E50417-G1140-C344-A5, Release date 11.2012
Cause
Message
CO+/–
MT+/–
ST+/– *)
ST+/– *)
CA+/–
SIPROTEC, 7SK80, Manual
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