STEERING GEAR SYSTEM

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GENERAL INFORMATION – Control System


The Steering Gear is a high performance system using the latest development in marine control technology. This system is capable of controlling twin rudder vessel from one or more
control stations.


Available Features

Flexible control from Center, Port or STBD stations on Bridge
The available features of the system are as follows:
• Auto Pilot
• Combination in Rudder Control (Follow Up Mode)
• Tillers (Non Follow Up mode) Setup &
Calibration The system setup and calibration can be maintained through onsite service and/or software parameters (password protected)

SYSTEM COMPONENTS – Central Processing Unit (PLC)

Description
The PLC supervises all input information like low voltage and low oil level and at the same time controls the output
signal for the rudder actuator. The position of the Rudders have an angle equally divided to Port and STBD direction.

Housing Connections
All the components are housed in the enclosure of the Starter Box where dust and moisture intrusion is prevented.
All units are not waterproof and therefore should not be immersed in liquid or washed. The units should also not be welded, beaten, smashed or dropped.
All connections to the PLC are hardwired into pluggable connectors on the PLC board. See electrical drawing

Rudders – Control Signal
The command of the system can take place from the Central Wheel Station or the Port or STBD tiller station.
The PLC drives the rudders through the electromechanical
actuators (solenoid valves) where the last ones are controlled by a Pulse control signal (Solid State Relays). 
During the operation, the PLC supervises all critical values and functions of the system and prompts an Alarm whenever something goes out of limits. Limits are entered as Set Points and are password protected.

OPERATION of CONTROL STATION


Description
There are three stations available on the bridge to drive the Steering Gear. The central one has a wheel and two tillers. The Port Station has three tillers, one central for common drive and the other two for separated driving of Port & STBD rudder respectively. The same applies on the STBD Station.
The wheel operates in Follow Up Combination mode and drives both rudders at the same time with a common command. The central analogue tillers of the side stations are also operates in Follow Up Combination mode and drives both rudders at the same time with a common command. The Non Follow Up mode can be selected by the NFU Switch. In Non Follow Up mode the side digital tillers of each station may drive each rudder separately and electrically (directly without PLC interference).

Operation Mode : 

The Operation mode of the system is selected from a switch (Operation Switch) with the below positions:
a) Center Combination
b) Center Tiller
c) Port Combination
d) Port Tiller
e) Stbd Combination
f) Stbd Tiller
There are three HMIs; one on the Central and from one on Port & STBD station. The HMI displays the angle of the rudders, the position of the wheel, an Alarm History and all alarm functions. The system operation can be started by the HMI and its running condition is displayed as well.

Alarms Operation
The system has an Alarm History feature where all alarm are registered. The user may find active or inactive alarms. All the alarms has a time stamp and detailed comments. Active alarms and acknowledged ones can easily be identified by the different colour they have.
The system will notify by an alarm for critical failures like the Main Power, the Backup Power, a motor overload, a low voltage or a low oil level. Authorised technical stuff may also
calibrate the -10V to +10V DC control signals via the HMI service page (password protected).
Emergency Operation
The Non Follow Up Operation procedure acts as emergency operation as well. The rudders should be operated in Non Follow Up mode in case of PLC lost or failure. The side digital
tillers are electrically connected to the actuators and can operate without the PLC. During a power failure, rudders remain at last ordered position.

ELECTRICAL POWER

Power requirements for the Electropneumatic Electronic Control System are:
• 220 V AC power supply – 10A
• 24 V DC supply from emergency
Power Switch Two sources of power must be provided; a primary source and a secondary one. The switching from main power supply to the emergency one and vice versa is automatically. Both supplies are parallel connected via bridges.