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Ships battery maintenance guidance
Various means of ships battery servicing
Battery are frequently used
to provide a low-voltage d.c. supply to certain
equipment onboard. To provide these services the appropriate size and type of
battery must be used and should be regularly serviced. Two main types
of battery are used on board ship: the lead—acid and the alkaline type,
together with various circuits and control gear.
To be available when required batteries must be maintained in a fully
charged condition. Where lead—acid batteries are used this can be
achieved by a constant trickle charge. Otherwise, for both types of
battery, a regular charge-up is necessary.
A measure of the state of charge can be obtained by using a
hydrometer. This is a device for measuring the specific gravity of a
liquid. A syringe-type hydrometer is shown in Figure above. A sample of
electrolyte is taken from each cell in turn and its specific gravity is
measured by reading the float level. All specific gravity values for the
individual cells in a battery should read much the same.
gravity reading can be related to the state of charge of the battery. The
specific gravity reading must be corrected for the temperature of the
electrolyte. The value for a fully charged lead-acid battery is 1.280 at
15°C. For an alkaline battery the specific gravity does not alter much
during charge and discharge but gradually falls over a long period:
when a value of 1.160 is reached it should be replaced.
Fig:Syringe type hydrometer
The electrolyte level should be maintained just above the top of the
plates. Any liquid loss due to evaporation or chemical action should be
replaced with distilled water. Only in an emergency should other water
be used. It is not usual to add electrolyte to batteries.
A battery must be kept clean and dry. If dirt deposits build up or spilt
electrolyte remains on the casing, stray currents may flow and discharge
the battery. Corrosion of the casing could also occur. The battery
terminals should be kept clean and smeared with a petroleum jelly. The
small vents in the cell caps should be clear at all times.
Cell voltage readings are useful if taken while the battery is
discharging. All cells should give about the same voltage reading, This
test method is of particular value with alkaline batteries, where specific
gravity readings for the electrolyte do not indicate the state of charge.
- A.C. motors for ships machinery
Supplying alternating current to a coil which is free to rotate in a magnetic field will not produce a motor effect since the current is constantly changing direction. Use is therefore made in an induction or squirrel cage motor of a rotating magnetic field produced by three separately phased windings in the stator. ...
Use of A.C. generatorsA coil of wire rotating in a magnetic field produces a current. The current can be brought out to two slip rings which are insulated from the shaft. Carbon bushes rest on these rings as they rotate and collect the current for use in an external circuit. Current collected in this way will be alternating, that is, changing in direction and rising and falling in value. To increase the current produced, additional sets of poles may be introduced....
D.C. motors for ships machinery When a current is supplied to a single coil of wire in a magnetic field a force is created which rotates the coil. This is a similar situation to the generation of current by a coil moving in a magnetic field. In fact generators and motors are almost interchangeable, depending upon which two of magnetic field, current and motion are provided.....
Use of D.C. generatorsA current is produced when a single coil of wire is rotated in a magnetic field. When the current is collected using a ring which is split into two halves (a commutator), a direct or single direction current is produced. The current produced may be increased by the use of many turns of wire and additional magnetic fields....
Emergency power supply for ships machinery operation
In the event of a main generating system failure an emergency supply of electricity is required for essential services. This can be supplied by batteries, but most merchant ships have an emergency generator. The unit is diesel driven and located outside of the machinery space .
Maintenance requirement for ships electrical equipment
With all types of electrical equipment cleanliness is essential for good operation. Electrical connections must be sound and any signs of sparking should be investigated. Parts subject to wear must be examined and replaced when necessary. ...
Choice of batteries for ships machinery spaces - Lead acid and alkaline batteries
The battery is a convenient means of storing electricity. It is used on many ships as an instantly available emergency supply. It may also be used on a regular basis to provide a low-voltage d.c. supply to certain equipment.....
Ships battery maintenance guidance The electrolyte level should be maintained just above the top of the plates. Any liquid loss due to evaporation or chemical action should be replaced with distilled water. Only in an emergency should other water be used. It is not usual to add electrolyte to batteries.....
Operating characteristics of battery for ships machinery spaces
Having been 'discharged' by delivering electrical power a battery must then be 'charged' by receiving electrical power. To charge the battery an amount of electrical power must be provided in the order of the capacity.....
Insulation resistance measurement
Good insulation resistance is essential to the correct operation of electrical equipment. A means must be available therefore to measure insulation resistance. Readings taken regularly will give an indication as to when and where corrective action, maintenance, servicing, etc., is required....
Use of navigational light circuitsThe supply to the navigation lights circuit must be maintained under all circumstances and special provisions are therefore made. To avoid any possibility of accidental open circuits the distribution board for the navigation lights supplies no other circuit.....
Ward—Leonard speed control system
As a very flexible, reliable means of motor speed control the Ward-Leonard system is unmatched.The system is made up of a driving motor which runs at almost constant speed and powers a d.c. generator .....
- Danger of electric shock to human bodyThe resistance of the human body is quite high only when the skin is dry. The danger of electric shock is therefore much greater for persons working in a hot, humid atmosphere since this leads to wetness from body perspiration.....
Marine machineries - Useful tags
Marine diesel engines ||Steam generating plant ||Air conditioning system ||Compressed air ||Marine batteries ||Cargo refrigeration ||Centrifugal pump ||Various coolers ||Emergency power supply ||Exhaust gas heat exchangers ||Feed system ||Feed extraction pump ||
Flow measurement || Four stroke engines || Fuel injector || Fuel oil system || Fuel oil treatment ||Gearboxes || Governor ||
Marine incinerator ||
Lub oil filters ||
MAN B&W engine ||
Marine condensers ||
Oily water separator ||
Overspeed protection devices ||
Piston & piston rings ||
Crankshaft deflection ||
Marine pumps ||
Various refrigerants ||
Sewage treatment plant ||
Starting air system ||
Steam turbines ||
Steering gear ||
Sulzer engine ||
Turbine gearing ||
Two stroke engines ||
UMS operations ||
Drydocking & major repairs ||
Critical machinery ||
Deck machineries & cargo gears
|| Control and instrumentation
||Engine room safety ||
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