Functions
2.4 Command Processing
SIPROTEC, 7SC805, Manual
C53000-G1140-C380-1, Release date 05.2014
50
2.4.4
Switchgear Interlocking
System interlocking is executed by the user-defined logic (CFC).
2.4.4.1
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 (with
IEC61850: The inter-relay communication with GOOSE is performed 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 activation of "Normal/Test"-key switch,
• For automatic commands, via command processing. by CFC and deactivated interlocking recognition,
• For local / remote commands, using an additional interlocking disable command.
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 indi-
cations. The indications designated with *) are displayed in the shown form in the Web Monitor in the event
logs, for DIGSI they appear in the spontaneous indications.
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/1/. The following figure shows operational indications relating to command execution and operation re-
sponse information for successful switching of the circuit breaker.
Type of Command
Command
Cause
Message
Control issued
Switching
CO
CO+/–
Manual tagging (positive / negative)
Manual tagging
MT
MT+/–
Information state command, input blocking
Input blocking
ST
ST+/– *)
Information state command, output blocking
Output blocking
ST
ST+/– *)
Cancel command
Cancel
CA
CA+/–
