Section
6 Control, monitoring and electrical equipment
6.1 Control
6.1.2 All steering systems are to be operated from the craft's control
station.
6.1.3 If steering systems can also be operated from other positions, then two-way
communication is to be arranged between the control station and these other
positions.
6.1.4 Steering control is to be provided:
-
For the main steering unit, both at the control station and in the
steering unit compartment, where applicable;
-
Where the main steering unit is arranged by two independent control
systems, both operable from the control station. This does not require duplication
of the steering wheel or steering lever. Where the control system consists of a
hydraulic telemotor, a second independent system need not be fitted.
-
For the auxiliary steering unit, in the steering unit compartment and,
if power operated, it is also to be operable from the control station and is to be
independent of the control system for the main steering system.
6.1.5 Electrical control systems are to be independent and separated as far as is
practicable throughout their length.
6.1.6 Any main and auxiliary steering unit control system operable from the
control station is to comply with the following:
-
Means are to be provided in the steering unit compartment, if
applicable, for disconnecting any control system operable at the control station
from the steering unit it serves;
-
The system is to be capable of being brought into operation from a
position on the control station.
6.1.7 Appropriate operating instructions with a block diagram showing the
change-over procedures for steering unit control systems and steering unit actuating
systems are to be permanently displayed at the control station and in the steering unit
compartment, if applicable.
6.1.8 Arrangements for failure detection are to be provided with self-monitoring
capabilities. In the event of failure being detected, an audible and individual visual
alarm is to be initiated on the navigating bridge. See
Pt 14, Ch 1, 6.2 Monitoring and alarms. Where the system
failure alarms for hydraulic lock, see
Table 1.6.1 Alarms, are provided, appropriate instructions are to
be placed on the control station to shut down the system at fault.
6.1.9 In the event of detecting a control system failure, which is likely to cause
uncontrolled rudder movements, see
Table 1.6.1 Alarms, the rudder is to retain its position at the
time of failure without manual intervention. Alternatively, consideration will be given
to the rudder moving to and retaining a position which is necessary for safe navigation
of the craft or to return to the mid-ship position where technical justification is
submitted and is found to be satisfactory.
6.2 Monitoring and alarms
6.2.2 The angular
position of the steering mechanism is to:
-
Where the main steering
unit is power operated, be indicated at the control station, and other
positions as applicable. The angular indication is to be independent
of the steering unit control system; and is to indicate any abnormal
responses or malfunctions. The logic of such feedback and indications
are to be consistent with the other alarms and indications so that
in an emergency operators are unlikely to be confused.
-
Be recognisable
in the steering unit compartment, if applicable.
6.2.4 Steering
control systems are to be monitored and an audible and visual alarm
is to be initiated on the navigation bridge in the event of:
- failure of the control system, including command and fee back
circuits; or
- unacceptable deviation between the rudder order and actual rudder
position and/or unacceptable delay in response to changes in the rudder
order.
Table 1.6.1 Alarms
| Item
|
Alarm
|
Note
|
| Angular position of the Steering
Mechanism
|
-
|
Indication, see
Pt 14, Ch 1, 6.1 Control 6.1.7
|
|
|
Failure
|
See
Pt 14, Ch 1, 6.2 Monitoring and alarms 6.2.4
|
| Earthing on AC and DC circuits
|
Fault
|
If galvanically isolated
from the ship’s network
|
| Data communication
|
Error
|
Where the data deviates
from expected value, sequence or timing
|
| Steering power units, power
|
Failure
|
-
|
| Steering motors
|
Overload Single
phase
|
For alarm and running
indication locations, see
Pt 14, Ch 1, 6.3 Electrical equipment 6.3.3 and Pt 14, Ch 1, 6.3 Electrical equipment 6.3.4
|
| Control system
|
Failure
|
See
Pt 14, Ch 1, 6.2 Monitoring and alarms 6.2.4
|
| Control system power
|
Failure
|
-
|
| Steering gear hydraulic oil tank
level
|
Low
|
Each reservoir to be
monitored. For Alarm locations, see
Pt 14, Ch 1, 6.3 Electrical equipment 6.3.5
|
| Auto pilot
|
Failure
|
Running
indication
|
| Hydraulic oil temperature
|
High
|
Where oil cooler is
fitted
|
| Hydraulic lock
|
Fault
|
Where more than one
system (either power or control) can be operated simultaneously each system
is to be monitored see Note
|
| Hydraulic oil filter differential
pressure
|
High
|
When oil filters are
fitted
|
Note This alarm is to
identify the system at fault and to be activated when (for example):
- position of the variable displacement pump control
system does not correspond with given order; or
- incorrect position of 3-way full flow valve or
similar in constant delivery pump system is detected.
|
6.3 Electrical equipment
6.3.1 Short
circuit protection, and overload alarm and, in the case of polyphase
circuits, an alarm to indicate failure of any one of the phases is
to be provided for each main and auxiliary motor circuit. Protective
devices are to operate at not less than twice the full load current
of the motor or circuit protected and are to allow excess current
to pass during the normal accelerating period of the motors.
6.3.2 Where
steering motor circuits are supplied by converters, consideration
will be given to arrangements that provide an equivalent level of
safety, reliability, availability and indication to those specified
in Pt 14, Ch 1, 6.3 Electrical equipment 6.3.1, provided that technical
justification is submitted.
6.3.4 Indicators
for running indication of each main and auxiliary motor are to be
installed on the control station and at a suitable main machinery
control position.
6.3.5 A low-level
alarm is to be provided for each steering system hydraulic fluid reservoir
to give the earliest practicable indication of hydraulic fluid leakage.
Alarms are to be given on the navigation bridge and in the machinery
space where they can be readily observed.
6.3.6 Two exclusive
circuits are to be provided for each electric or electrohydraulic
steering unit arrangement consisting of one or more electric motors.
6.3.7 Each of
these circuits is to be fed from the main switchboard. One of these
circuits may pass through the emergency switchboard.
6.3.8 One of
these circuits may be connected to the motor of an associated auxiliary
electric or electrohydraulic power unit.
6.3.9 Each of
these circuits is to have adequate capacity to supply all the motors
which can be connected to it and which can operate simultaneously.
6.3.10 These
circuits are to be separated throughout their length as widely as
is practicable.
6.3.11 Each
main and auxiliary electric control system which is to be operated
from the control station is to comply with the following:
-
It is to be served
with electric power by a separate circuit supplied from the associated
steering unit power circuit, from a point within the steering unit
compartment, or directly from the same section of switchboard busbars,
main or emergency, to which the associated steering unit power circuit
is connected.
-
Each separate circuit
is to be provided with short circuit protection only.
|