ABB Relion 611 Series, Technical Manual

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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 apparatus
already is in the right position, the maximum pulse length is given.
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 several 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 canceling: cancels the controlling of a selected object.
In direct operation, a single message is used to initiate the control action of a physical
device. The direct operation method uses less communication network capacity and
bandwidth than the SBO method, because the procedure needs fewer messages for
accurate operation.
1MRS757454 D
Section 8
Control functions
611 series 399
Technical Manual