Functions
2.27 Command Processing
SIPROTEC, 7SD5, Manual
C53000-G1176-C169-5, Release date 02.2011
488
2.27.1.3 Interlocking
Interlocking can be executed by the user-defined logic (CFC). Switchgear interlocking checks in a SI-
CAM/SIPROTEC 4 system are normally divided in the following groups:
• System interlocking checked by a central control system (for interbay interlocking),
• Zone controlled / bay interlocking checked in the bay device (for the feeder).
• Cross-bay interlocking via GOOSE messages directly between bay controllers and protection relays (with
rollout of IEC 61850; inter-relay communication by GOOSE messaging is performed via the EN100 module)
System interlocking is based on the process image in the central device. Zone controlled / bay interlocking
relies on the object database (feedback information) of the bay unit (here the SIPROTEC 4 relay) as was de-
termined during configuration (see SIPROTEC 4 System Description).
The extent of the interlocking checks is determined by the configuration and interlocking logic of the relay. For
more information on GOOSE messaging, please refer to the SIPROTEC 4 System Description.
Switching objects that require system interlocking in a central control system are marked by a specific param-
eter inside the bay unit (via configuration matrix).
For all commands, operation with interlocking (normal mode) or without interlocking (test mode) can be select-
ed:
• For local commands by reprogramming the settings with password check,
• 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).
De-interlocked or non-interlocked switching means that the configured interlock conditions are not tested.
Interlocked switching means that all configured interlocking conditions are checked within the command pro-
cessing. If a condition could not be fulfilled, the command will be rejected by an indication with a minus added
to it, e.g. „CO–“, followed by an operation response information. The command is rejected if a synchronism
check is carried out before closing and the conditions for synchronism are not fulfilled. Table 2-25 shows some
types of commands and indications. The indications marked with *) are displayed only in the event logs on the
device display; for DIGSI they appear in spontaneous indications.
Table 2-25
Command types and corresponding indications
The plus sign in the indication is a confirmation of the command execution: The command output has a positive
result, as expected. A minus sign means a negative, i.e. an unexpected result; the command was rejected.
Figure 2-237 shows an example for successful switching of the circuit breaker in the Event Log (command and
feedback).
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 overriding or abort are not tested, i.e. are executed in-
dependently of the interlockings.
Type of Command
Control
Cause
Indication
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+/–
