3 Separation of control systems and components
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Statutory Documents - IMO Publications and Documents - Circulars - Maritime Safety Committee - MSC.1/Circular.1398 – Unified Interpretation of SOLAS Regulation II-2/29 – (10 June 2011) - Annex – Mechanical, Hydraulic and Electrical Independency and Failure Detection and Response of Steering Control Systems - 3 Separation of control systems and components

3 Separation of control systems and components

  3.1 General

 Wires, terminals and the components for duplicated steering gear control systems installed in units, control boxes, switchboards or bridge consoles should be separated as far as practicable. Where physical separation is not practicable, separation may be achieved by means of a fire retardant plate.

  3.2 Steering wheel or steering lever

 All electric components of the steering gear control systems should be duplicated. This does not require duplication of the steering wheel or steering lever.

  3.3 Steering mode selector switch

 If a joint steering mode selector switch (uniaxial switch) is employed for both steering gear control systems, the connections for the circuits of the control systems should be divided accordingly and separated from each other by an isolating plate or by air gap.

  3.4 Follow-up amplifier

 In the case of double follow-up control (see appendix, example 2), the amplifiers should be designed and fed so as to be electrically and mechanically separated. In the case of non-follow-up control and follow-up control, it should be ensured that the follow-up amplifiers are protected selectively (see appendix, example 3).

  3.5 Additional control systems

 Control circuits for additional control systems, e.g., steering lever or autopilot should be designed for all-pole disconnection (see appendix, examples 1, 2 and 3).

  3.6 Feed-back units and limit switches

 The feed-back units and limit switches, if any, for the steering gear control systems should be separated electrically and mechanically connected to the rudder stock or actuator separately.

  3.7 Hydraulic control components

  3.7.1 Hydraulic system components in the power actuating or hydraulic servo systems controlling the power systems of the steering gear (e.g., solenoid valves, magnetic valves) should be considered as part of the steering gear control system and should be duplicated and separated.

  3.7.2 Hydraulic system components in the steering gear control system that are part of a power unit may be regarded as being duplicated and separated when there are two or more separate power units provided and the piping to each power unit can be isolated.

Parent topic: Annex – Mechanical, Hydraulic and Electrical Independency and Failure Detection and Response of Steering Control Systems
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