Rolls-Royce Helicon X3, User Manual

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System Description
3
Page 13 of 16 Doc. No.: 13S000411
Revision: A Copyright © 2010 Rolls-Royce plc
automatically switch to and engage the Backup Control.
Lever order signals and feedback are monitored and verified against adjustable alarm
limits. If the signals exceed the limits this will release an alarm to the alarm plant with
a visual and audible system failure alarm on the manoeuvre stations.
4.2.3 Backup Control Operation
If a failure occurs on important parts of the Normal control for the Pitch/Azimuth/RPM
control function, the control will automatically be switched over to the backup control
system. A system failure audible and visible alarm will be activated on each of the
control panels.
The thruster control will continue to follow the lever in command, and command
transfer is done by using the common in command buttons. The command can be
transferred between all bridge position and the bridge control levers will continue to
work as in Normal Control.
A failure that occurs on important parts of the Backup control for the Pitch/Azimuth/
RPM control function, will not affect the Normal control system. If a system failure
occurs on the Backup Control an audible and visible alarm will be activated on each of
the control panels.
4.2.4 Backup Control Limitations
The backup control system has only interface to the control levers. The backup control
system does not have interface to external control systems like Dynpos, Joystick or
Autopilot.
Note: No azimuth restrictions or load control functions are included in the
backup system.
When operating using the backup system, the operator must be careful not to overload
the engine or the propeller system.
4.2.5 Local Control
Local control is used if both the normal control and the backup control fail to operate the
thruster azimuth. The thruster azimuth can be operated locally on the actuator unit. The
Control System must first be disconnected from the actuator unit. This can be done by
means of the Local Control switch mounted in front of the Actuator Interface Unit, or
by disconnecting the plug from the actuator unit. If frequency converter used, operate
service switch inside converter cabinet.
The Thruster Instruction Manual will give more details for Local Control operation.
4.2.6 Azimuth Indication
The azimuth indication system independent of the normal control system by means of
separate transmitters and electronic circuits. The Azimuth indicators are connected in
series, and are driven from the Backup Control system.