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Файл:English for marine electro-technical officers. Supplementary book. Учебное пособие
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51
An alternative or standby power supply is fed from the
emergency switchboard.
A changeover switch on the Navigation Light Panel selects the main or standby power supply.
The Navigation Light Panel has indicator lamps and an
audible alarm to warn of any lamp or lamp-circuit failure. Each
lamp circuit has an alarm relay which monitors the lamp current. The relay may be electromagnetic or electronic.
Answer the questions:
1. What is the light output from a discharge lamp gen-
erated by?
2. What are the most common metal vapours employed
in discharge lamps?
3. What does a suitable voltage applied between the
electrodes of a discharge lamp cause?
4. Why must the discharge lamp current be carefully
controlled?
5. What are the number, position and visible range of
navigation lights aboard ships prescribed by?
6. What navigation running lights do you know?
7. What range must the masthead light(s) be visible
from?
8. What lamps are used to achieve a good visibility?
9. Where is each light monitored from?
52
10. Where is an alternative or standby power supply fed
from?
11. Why does the Navigation Light Panel have indicator
lamps and an audible alarm?
Words and expressions (4.5, 4.6)
emergency lights may be
supplied from
аварийное освещение может
подводиться от
low-ohm continuity
непрерывность с низким
сопротивлением
single earth fault
неисправность, связанная
с единичным заземлением
blow fuse
перегоревший
предохранитель
to rupture
разрушиться, пробить
to insert
вставлять, включать
to cause an accidental shortcircuit
вызвать случайное короткое
замыкание
lampholder
патрон лампы
to remain charged for
a while after switch off
оставлять заряженным
на некоторое время после вы-
ключения
particular care
особенное внимание
53
4.5. Emergency lighting
Depending on the ship's classification, e.g. ferry, ro-ro,
gas carrier, etc., and tonnage the Safety of Life at Sea (SOLAS)
Convention prescribes minimum requirements for emergency
lighting throughout the vessel.
Emergency light fittings are specially identified, often
with a red disc, to indicate their function. Most of the emergency lighting is continually powered from the ship's emergency
switchboard at 220 V a.c.
A few emergency lights may be supplied from the ship's
24 V d.c. battery, e.g. at the radio-telephone position in the
wheelhouse, the main machinery spaces and the steering flat.
4.6. Maintenance of lighting fittings
The performance of electric lamps will deteriorate with
time. Eventually they fail and the lamps must be replaced.
Simple lamp replacement becomes the most obvious maintenance task. When a luminaire fails to light-up when switched
on, it is natural to suspect lamp failure. If this does not solve
the problem, checks on the lamp control equipment and power
supply must follow.
An incandescent lamp may be checked (out of circuit)
for low-ohm continuity using a multimeter. If the lamp appears
intact then the fault must lie in the supply or its connections.
54
Voltage and continuity checks of the supply, fuse / MCB and
ballast circuit must be applied. Remember that a single earth
fault on an insulated two-wire lighting supply will not blow
a fuse. However, a similar earth fault on an earthed supply system (as used for a 110 V transformer supply to deck sockets for
portable tools and handlamps) will blow a fuse.
A maintenance check list:
Remember that it is good practice to replace both fuses
after clearing a fault which has ruptured only one of them.
When replacing a lamp, ensure that the circuit is dead
and isolated while removing the old lamp and inserting the new
one. The glass bulb or tube of an old and corroded fitting may
break loose from its end-cap while attempting to remove the
lamp. If the supply is still connected, it is relatively easy to
cause an accidental short-circuit during the removal process
and the corresponding arc flash may cause blindness, burns
and fire.
Always replace a lamp with the correct size, voltage
and power rating for the fitting it is housed in. Overheating and
fire can easily result by using a higher powered incandescent
lamp than the fitting was designed for. Check the lampholder
wire connections behind the lampholder for signs of overheating (hard, brittle insulation on the wires) and replace if necessary.
Take care when disposing of lamps, particularly discharge tubes, which should be broken (outdoors) into a container (e.g. a strong plastic bag) to avoid handling the debris.
55
Remember that in a fluorescent lamp circuit the capacitor may remain charged for a while after switch off unless fitted with a discharge resistor. Play safe, discharge the capacitor
with a screwdriver blade before touching its terminals.
Cleaning of the lamp glass and reflectors is essential for
safety and necessary to maintain the luminous efficiency of the
luminaire.
Particular care should be paid to the maintenance of the
watertight integrity of exposed luminaires (e.g. for navigation,
signal and deck lighting) at their flanged joints and cable gland
entry. Similarly, a regular inspection of all portable handlamps
and portable cargo light fittings, together with their flexible
cables and supply plugs, should be undertaken.
Answer the questions:
1. What document prescribes minimum requirements
for emergency lighting throughout the vessel?
2. Where is the most of the emergency lighting continu-
ally powered from?
3. What are your actions when a lamp fails to light-up?
4. What are the main points of a check-list?
Words and expressions (4.7, 4.8)
to comprise
охватывать, включать
sea-water cooling pumps
насосы, которые
охлаждаются морской водой
high and low-pressure and
выключатель высокого
56
temperature switch
и низкого давления
и температуры
safety cut-out for overcurrent
безопасное отключение для
тока перегрузки
loss of refrigerant
потеря хладогента
central single-duct type
центрального
одноканального типа
routine power supplies
электропитание для
постоянных нужд
emergency battery supplies
аварийное питание
от батареи
standby role
резерв
vital
жизненно необходимый
the only source of emergency power
единственный источник
аварийного питания
4.7. Refrigeration and Air Conditioning
The electrical aspects of accommodation air conditioning (A/C) comprises the power equipment of motors and starters for the compressor(s), fans and sea-water cooling pumps.
Associated control equipment will include electric solenoid
valves, high and low-pressure and temperature switches together with safety cut-outs for overcurrent, loss of refrigerant,
low compressor oil pressure, etc.
57
The usual air-conditioning system used for the accommodation spaces of cargo ships is the central single-duct type.
In its simplest form a single compressor serves the whole accommodation.
4.8. Battery supplies
A properly maintained storage battery will instantly
supply electric power when required. This feature makes a battery the key element in the provision of essential and emergency power supplies on board ships.
Essential routine power supplies, e.g. for radio equipment, telephone exchange, fire detection, general alarm circuits
etc., are often supplied from two sets of batteries worked on
a regular charge / discharge cycle.
Emergency battery supplies, e.g. for emergency generator start-up and emergency lighting, are used in a standby role
to give power when the main supply fails.
Ships' batteries are usually rated at a nominal voltage of
24 V d.c. In some cases a battery system of 110 V or 220 V
d.c. may be used where a large amount of emergency lighting
and power is vital or where a battery is the only source of
emergency power.
The two main types of rechargeable battery cell are:
- lead-acid;
- alkalin.
58
Answer the questions:
1. What does the electrical aspects of accommodation
air conditioning (A/C) comprise?
2. What type is the usual air-conditioning system?
3. What are essential routine power supplies often sup-
plied from?
4. What cases are emergency battery supplies used in?
5. What are nominal voltages of ships’ batteries?
59
5. SPECIAL ELECTRICAL PRACTICE FOR OIL,
GAS AND CHEMICAL TANKERS
Words and expressions (5.0, 5.1)
to be subject to
регулироваться, подвергаться
to prevent the hazard of fire
and explosion
предотвратить опасность
пожара и взрыва
caused by
вызванное чем-либо
to permit
разрешать
earth loop resistance test
проверка контура заземления
continuity resistance test
проверка наличия
сопротивления
intrinsically safe apparatus
and circuits
искробезопасные приборы
и цепи
excess
избыток
inadvertently
непреднамеренно
combustible
воспламеняемый
to design
конструировать
energy-storing properties
энергосберегающие свойства
appreciable value
существенное значение
to detach
отсоединять
original certified state
первоначальное (исходное)
состояние
60
to forbid
запрещать
meticulous care
тщательный уход
flameproof luminaire
огнестойкий светильник
to reduce the enclosure
strength
для уменьшения прочности
корпуса
to deteriorate
ухудшать
to secure
закрепить
signs of corrosion or pitting
признаки коррозии
или точечной коррозии
blind tapped holes
глухие резьбовые отверстия
over-tightened
пережатый
Ships and offshore installations that transport, process
and store bulk quantities of oil, gas and liquid chemicals are
subject to special codes of practice regarding their electrical
installations. Statutory authorities and classification societies
generally base their recommendations on Publication 92 of the
International Electrotechnical Commission (IEC).
The object of all such guidance is to prevent the hazards
of fire and explosion occurring on board these tank ships.
Spaces in tankers where explosive gas-air mixtures may
be expected to be present are called dangerous or hazardous.
All other areas being regarded as safe.
The best way to avoid explosions caused by electrical
equipment is simply not to install such equipment in the haz-
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