ABB RER620 Technical Manual page 281

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RER620
Technical Manual
not bypassed with the interlocking bypass functionality since they always have higher
priority.
Open and close operations
The corresponding open and close operations are available via communication, binary
inputs or LHMI commands. As a prerequisite for control commands, there are enable and
block functionalities for both the close and open commands. If the control command is
executed against the blocking, or if the enabling of the corresponding command is not
valid, SCBXCBR generates an error message.
Open and close pulse widths
The pulse width type can be defined with the Adaptive pulse setting. The function provides
two modes to characterize the opening and closing pulse widths. When the Adaptive pulse
is set to TRUE, it causes a variable pulse width, which means that the output pulse is
deactivated when the object state shows that the circuit breaker has entered the correct
state. When the Adaptive pulse is set to FALSE, the function always uses the maximum
pulse width, defined by the user-configurable Pulse length setting. The Pulse length
setting is the same for both the opening and closing commands. When the circuit breaker
already is in the right position, the maximum pulse length is given. Note that the Pulse
length setting does not affect the length of the trip pulse.
Control methods
The command execution mode can be set with the Control model setting. The alternatives
for command execution are direct control and secured object control, which can be used
to secure controlling.
The secured object control SBO is an important feature of the communication protocols
that support horizontal communication, because the command reservation and
interlocking signals can be transferred with a bus. All secured control operations require
two-step commands: a selection step and an execution step. The secured object control is
responsible for the following tasks:
• Command authority: ensures that the command source is authorized to operate the
object
• Mutual exclusion: ensures that only one command source at a time can control the
object
• Interlocking: allows only safe commands
• Execution: supervises the command execution
• Command cancelling: cancels the controlling of a selected object.
In direct operate, a single message is used to initiate the control action of a physical device.
The direct operate method uses less communication network capacity and bandwidth than
the SBO method, because the procedure needs fewer messages for accurate operation.
Section 5
Control functions
275