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8/10/2019 electrical shop in a ship repair yard.pdf
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SEMINAR REPORT
SHIP PRODUCTION II
Electrical Shop in a Ship Repair Yard
10-October,2012
Submitted by:
Naseef PK
Nikhil KR
Rashid K
Mohammed Nizar PMSemester-VII
B.Tech in Naval Architecture
and Shipbuilding
DOST, CUSAT
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ELECTRICAL REPAIR SHOP
The electrical shop in a ship repair yard should be equipped and capable of
undertaking repairs and rewinding of full range of motors and generators of ships
and overhaul of electrical apparatus and switch gears. List of major equipments
here are:-
Electric Coil Winding machines
Industrial Furnaces
Dimmer stats
Quick way Armature winding machine with counter
Coil winding machinery with counter
Testing panel with dimmer stat
The potential for electrical shock hazards is greater in shipbuilding and repairthan in other industries, because workers stand on metal decks and often work in a wet
environment. Work on or around energized electrical equipment can expose workers
to electrocution, burns, or electrical shock. Before work is performed, energized
equipment must be guarded, de-energized, or appropriate PPE used to prevent worker
exposure.
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ELECTRICAL SHOP PLAN
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MAINTENANCE AND INSPECTION OF ELECTRICAL EQUIPMENT ON
THE SHIP
The electrical switchboards, section boards and their equipment, on board the ship, are
generally subjected to structural, climatic or electrical wear. In order to preserve their
integrity throughout the ship's life, it seemed necessary to develop recommendations
dealing with their maintenance and inspection.
Actions EVERY EVERY FIVE
YEAR YEARS
1. Electrical switchboards and section boards are to be visually X X
examined to assess the good operation and maintenance.
2. Electric equipment is to be examined for cleanliness. Where X X
deemed necessary, cleaning of electrical equipment.
(dust suction, wiping up oil water deposits)
3. It is to be checked that:
3.1 Cables or other electric equipment are still in the original X X
position. Any modification should be to the satisfaction
of the Society.
3.2 Cable penetration devices are still in good condition X X
3.3 No evidence of overheating, burning or tracking X X
3.4 Measuring equipment is in order. X X
3.5 Mechanical ventilation, if fitted, operates as required X X
3.6 Where a protection device has been replaced, its rating and, X X
where applicable, settings are to be verified.
4. Contacts and arc screens, if any, of all concerned devices are X
to be checked and reconditioned or replaced if necessary in
accordance with manufacturers recommendation.
Movable parts of the said devices are to be tested.
5. Tightening of connections and assemblies which may slacken X
is to be checked and tightened, if required, according to the
manufacturers recommendations. Thermograph aids may
be considered to detect hot spots.
6. Where accumulator batteries may be stored, the condition of X X
connections (salt deposits ...), the fastenings, the ventilation
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and the tray tightness are to be checked.
7. Where fitted, computer based systems are to be tested. X
Their original functions are to be unchanged.
8. An insulation measurement of any circuit in doubt is to be X
carried out. Any large decrease in values is to be
investigated and corrected.
9. All circuits are to be subject to insulation measurements for X
comparison with the insulation recordings previously
established. Corrective actions are to be carried out if the
values obtained are under 1k per volt.
10. Circuit interlocks, if any, are to be tested. X
11. Protective devices are to be tested. The electronic protective X
devices for generators and large consumers are to be tested
12. The operation of all emergency sources of power is to be tested, X X
including their automatic devices if any.
13. All automatic sequences, e.g. for synchronization, connection, X X
load shedding if any are to be tested as far as practicable.
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PROCESS FLOW FOR GENERATOR/MOTOR REPAIR
Identification of physical damage
Insulation check
Opening meeting between
representatives of yard and owner
Handing over of work to Electric
shop
Dismantling of parts
Re-check for damage
Cleaning of parts. Mainly fresh
water rinsing. If oil present, apply
chemicals.
Baking process done in OVENS
Apply varnish and check the
readings
Assemble the parts
Computerized checking of every
parameters
Curing period: Sometimes
need BAKING
Apply coating (eg: BETTOL)Advantage of usingBETTOL
Insulation
Anti-corrosive
Installation of Machinery
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MAIN SWITCH BOARD
One more important thing is the main switch board. All the machineries on ship that
consume electrical power should be connected to a main switch board. The system
should be designed in such a way that under all normal conditions of operation, power
should be distributed from main switch board.
The main switch boards are located in the center of the distribution or in engine
control room. They should be installed in such an area that in time of emergency such
as fire or flooding, they should be easily accessible. Thus they should be installed in
spaces away from the main machinery spaces.
In general a MSB should have the following boards,
1. 220V FEEDER PANEL
2. GROUP STARTER PANEL-2
3. 440V FEEDER PANEL-2
4. GEN-3 PANEL
5. TIE BREAKER & ESB BREAKER
6. SYNC PANEL
7.
GEN-2 PANEL
8.
GEN-1 PANEL9.
440V FEEDER PNL-1
10. GROUP STARTER PANEL-1
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ELECTRICAL DIAGRAMS
Different types of diagrams used in the ships and shop involves,
BLOCK DIAGRAM
SYSTEM DIAGRAM
CIRCUIT DIAGRAM
WIRING DIAGRAM
CONNECTION DIAGRAM
Block diagram
The block diagram is typically used for a higher level, less detailed description aimed
more at understanding the overall concepts and less at understanding the details of
implementation. In electrical engineering, a design will often begin as a very high
level block diagram, becoming more and more detailed block diagrams as the design
progresses, finally ending in block diagrams detailed enough that each individual
block can be easily implemented (at which point the block diagram is also a schematic
diagram). This is known astop down design.Geometric shapes are often used in the
diagram to aid interpretation and clarify meaning of the process or model. The
geometric shapes are connected by lines to indicate association and direction/order oftraversal. Each engineering discipline has their own meaning for each shape.
System diagram
The system diagram shows connections between different systems involved. It helps
the engineer to understand different interconnections between the systems. It also
helps to identify the corrections required when the problem is identified.
Circuit diagram
A circuit diagram (also known as an electrical diagram, elementary diagram,
or electronic schematic) is a simplified conventional graphical representation of
anelectrical circuit.Apictorial circuit diagram uses simple images of components,
while aschematic diagram shows the components of the circuit as simplified standard
symbols; both types show the connections between the devices,
includingpower andsignal connections. Arrangement of the components
interconnections on the diagram does not correspond to their physical locations in the
finished device. Unlike ablock diagram orlayout diagram,a circuit diagram showsthe actual wireconnectionsbeing used. The diagram does not show the physical
arrangement of components.
http://en.wikipedia.org/wiki/Top-down_and_bottom-up_designhttp://en.wikipedia.org/wiki/List_of_geometric_shapeshttp://en.wikipedia.org/wiki/Electrical_networkhttp://en.wikipedia.org/wiki/Pictorialhttp://en.wikipedia.org/wiki/Schematic_diagramhttp://en.wikipedia.org/wiki/Electric_powerhttp://en.wikipedia.org/wiki/Signal_(information_theory)http://en.wikipedia.org/wiki/Block_diagramhttp://en.wikipedia.org/wiki/Integrated_circuit_layouthttp://en.wikipedia.org/wiki/Electrical_connectionhttp://en.wikipedia.org/wiki/Electrical_connectionhttp://en.wikipedia.org/wiki/Integrated_circuit_layouthttp://en.wikipedia.org/wiki/Block_diagramhttp://en.wikipedia.org/wiki/Signal_(information_theory)http://en.wikipedia.org/wiki/Electric_powerhttp://en.wikipedia.org/wiki/Schematic_diagramhttp://en.wikipedia.org/wiki/Pictorialhttp://en.wikipedia.org/wiki/Electrical_networkhttp://en.wikipedia.org/wiki/List_of_geometric_shapeshttp://en.wikipedia.org/wiki/Top-down_and_bottom-up_design8/10/2019 electrical shop in a ship repair yard.pdf
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Wiring diagram
A wiring diagram is a simplified conventional pictorial representation of an electrical
circuit. It shows the components of the circuit as simplified shapes, and the power and
signal connections between the devices. A wiring diagram usually gives more
information about the relative position and arrangement of devices and terminals on
the devices, to help in building the device. This is unlike aschematic diagram wherethe arrangement of the components interconnections on the diagram does not
correspond to their physical locations in the finished device. A pictorial diagram
would show more detail of the physical appearance, whereas a wiring diagram uses a
more symbolic notation to emphasize interconnections over physical appearance.
Connection diagram
The detailed connections that have to be made are indicated in this diagram. Each andevery specification must be included in this diagram regarding connections.
http://en.wikipedia.org/wiki/Schematic_diagramhttp://en.wikipedia.org/wiki/Schematic_diagram8/10/2019 electrical shop in a ship repair yard.pdf
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TESTING
INSULATION RESISTANCE (MEGGER)
The insulation resistance (IR) test (also commonly known as a Megger) is a spot
insulation test which uses an applied DC voltage (typically either 250Vdc, 500Vdc or
1,000Vdc for low voltage equipment
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CURRENT (CLAMP METER)
Clamp meters are a very convenient testing instrument that permits current
measurements on a live conductor without circuit interruption. When making current
measurements with the ordinary multimeter, we need to cut wiring and connect the
instrument to the circuit under test. Using the clamp meter, however, we can measurecurrent by simply clamping on a conductor as illustrated in Fig.2. One of the
advantages of this method is that we can even measure a large current without shutting
off the circuit being tested.
VOLTAGE (MULTIMETER)
A multimeter is very useful in measuring and testing DC voltage. The
multimeter can be a standard multimeter, a digital multimeter (DMM), or a
auto-ranging digital multimeter. The source of the DC voltage can be from
batteries, circuits, transformers, or any other electronic device that operates on
DC voltage. Troubleshooting of DC electronics is made easier by using a
digital multimeter to test in-circuit DC voltage and compare the results to an
electrical schematic. Faulty components can be identified within the circuit in
order to make repairs.
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RESISTANCE (MULTIMETER)
An ohmmeter can be used to directly measure an unknown resistance R .This is
the simplest way to measure resistance. It is important to realize that an
ohmmeter cannot be used when the resistance is connected in a circuit and acurrent is flowing through it .
CONTINUITY (MULTIMETER)
One of the most basic uses of a multimeter is to test for continuity. Testing for
continuity basically means testing to see if there is an electric connection
between two points. If two points are electrically connected they are said to be
continuous. This brief guide explains how to use a digital multimeter to findout if there is an electric connection between two points.
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INSULATION CLASS
Electrical insulation is classified with its maximum allowable temperature. By
adopting an insulation technique of higher thermal endurance, electric instruments can be
downsized. In early times, the temperature classes of electric insulators were simply divided
into natural organics, inorganics, and combinations thereof. In the late 1930s, the types of
synthetic resins became diverse and their production volumes increased, with theirapplication range being gradually expanded to insulation. In the late 1940s, when silicone
resin became a popular insulator material, the H-class insulator was added to the temperature
classes, and it became increasingly necessary to find applications for heat resistant materials
in electric instruments.
CLASS YWithstands a temperature of up to 90C; typically made of cotton, silk, or paper.
e.g.: Cotton, silk and paper.
CLASS A
Withstands a temperature of up to 105C; reinforced Class-Y materials with
impregnated varnish or insulation oil.
e.g.: Cotton silk and paper all suitably impregnated or coated with oil or other
insulating compound.
CLASS E
Withstands atemperature of up to 120C.e.g.: Mica, asbestos and glass products all organic bounding substances.
CLASS B
Withstands a temperature of up to 130C. This has a form that inorganic
material is hardened with adhesives. This is the first insulator using this structure.e.g.: Mica, asbestos and glass products all with suitable bonding.
CLASS F
Withstands a temperature of up to 155C; for example, made of Class-B
materials that are upgraded with adhesives, silicone, and alkyd-resin varnish ofhigher thermal endurance.
e.g.: Mica asbestos and glass products all with inorganic bonding substances.
CLASS H
Withstands a temperature of up to 180C; for example, made of inorganic
material glued with silicone resinor adhesives of equivalent performance.e.g.: Mica, glass fibre, asbestos, silicon all with silicone as bonding material.
CLASS CWithstands a temperature of up to 180C or higher; made of100% inorganic
material.e.g.: Mica, porcelain, glass, quartz all with or without inorganic bonding material.
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PROTECTION CLASSDENOTED AS IP XY
Ingress Protection rating is used to specify the environmental protection - electrical enclosure
- of electrical equipment.
Ingress Protection (IP) ratings are developed by the European Committee for Electro
Technical Standardization (CENELEC)(NEMA IEC 60529 Degrees of Protection Provided
by Enclosures - IP Code), specifying the environmental protection the enclosure provides.
The IP rating normally has two (or three) numbers:
1.Protection from solid objects or materials
2.Protection from liquids (water)
Protection against mechanical impacts (commonly omitted, the thirdnumber is not a part of IEC 60529)
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MOTOR STARTERS
CAGE MOTOR
DIRECT ON LINE
DOL STARTER CONTROLSCHEMATIC DIAGRAM
STAR/DELTA
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AUTOTRANSFORMER
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ELECTRICAL SURVEY REQUIREMENT
GeneratorsA generator is a simple device to convert mechanical energy into electrical energy. Usually
they generate rotating current 50Hz or 60Hz leaving for direct-driven machines of the
following engine speeds of 500/600 RPM, 6001720RPM, 750/900 RPM, 100011200RPM,
1500/1800 RPM and 3000/3600RPM. The higher figures are mostly for smaller generatorsets or turbine driven machines.
Electric motorsElectric motors are simple devices to convert electrical energy into mechanical energy. AC
squirrel cagemotors have the same RPM restriction as AC generators. Motors area available
in different casings for fitting on a foundation or flange for fitting to a pump. Also various
protection classes against the ingress of solid particles and water area available, and for use in
an explosive
Environment increased safety "non sparking types" and flame proof motors are available.
CablesCables form the connections between the different parts of the electric installation and are
nowadays available as low-smoke , low toxic and even fire-resistant types. Application of
such more sophisticated cables will reduce the consequences and damage of a fire. The
commercially attractive PVC insulated types are vulnerable in case of fire. The insulation
burns causing short circuits. They generate high quantities of toxic and corrosive gases which
will damage a lot more of the installation than that damaged by the fire only. However, a
disadvantage of the low smoke types of cables is that their mechanical properties are
considerably less.
Switchboards and switchgear assembliesSwitchboards and other switchgear assemblies basically serve to connect and disconnect
generators and consumers to the main power supplysystem. They contain also theprotection
devices of the generators, the cables and the consumers against overload and short-circuits.
Switchboardsand other control-gear assembliescan be operated by engineers, but servicing
and maintenance and repairs should be carried outbyspecialists.Laws in most countries issue
a clearinstruction of how to power apart of an installation safely, to carry out
repairsand power up safely afterwards. It also defines skills andresponsibilities of the
operators andmaintenance people. The main differencesbetween an industrial switchboard
and a marine switchboard areprotection class IP23 with closed doors. In case of open doors,
protection class lP20, handrails, door catchersin open position, measuring andindicationinstruments to be able to
synchronise and for load sharingofboth power and current etc.
When electricpower is required forpropulsion of the ship, the source of
power is to be duplicated and the mainbus basin the main switchboard
is to be divided in two parts connected by a removable link for small
installations up to full-size circuit breakers with selective protection devices for large
installations. Duplicated essential consumers shallbe supplied each from a side of the switch
board,or when supplied from distribution-boards from separate
distribution-boards, each supplied from a side of the main switchboard.All of this with the
same target that a single fault does neither impair thepropulsion system nor impair
thehabitability for the crew. This single failure also includes a fire or other damage to a cabletray. Therefore thepower cables and control cables toessential duplicated consumers shall be
separated.
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Circuit breakers and contactorsA circuit breaker is designed to close and interrupt a short-circuit current a few times only
without maintenance.A contactor is designed to withstand thousands of times the starting
currents of electric motors. A circuit breaker is therefore not suitable tostart a large motor.
Switching capabilitiesare given under different conditions. Some manufacturers give a
capacity only oncepossible.
Moulded case circuit breakers, especially the current limiting types can be replaced as a
complete unit only.
Emergency generatorAn emergency generator is a generator with the same characteristics as a main generator but
located in a space separated from the main generators and independent of any equipment
outside this space. So starting equipment such as an air bottle with a non-return valve of the
engine room starting air system, a
separate fuel tank, an emergency switchboard in the same space as the generator set to limit
the possibility of failure of the emergency system in case of failure of a space, This all to
ensure continuity of emergency power as much as possible
Starting devicesStarting devices are used to limit the in-rush current of a consumer when connected to the
main power supply to an acceptable value. That is to a value that does not disturb the proper
functioning of the other devices in the installation. Starting devices are also used to limit the
starting torque of an electric motor.
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HAZARDOUS AREAS
Dangerous areas are those areas where due to the continuous or part time
presence of gases or flammable liquids or even explosive dust, the risk of explosion exists.
Dangerous areas are, for example, the tanks of a tanker and the deck above, the cargo-handling area, pump room etc..but also the car-deck of a ferry where cars are stowed with
fuel in their tanks, a helicopter refilling station on a yacht and a paint store or the hold of a
dry-cargo ship certified for the carriage of dangerous goods.
Cost-effective solution number one is not to install any electrical equipment
In dangerous areas. The dangerous areas are divided into the following
zones:
Zone 0Areas where an explosive-gas atmosphere is continuouslypresent or Canbepresent. For
example, a cargo tank of a crude oil tanker, oil productstanker or chemical tanker carrying flammable liquids other than liquefiedgases having a nash
point not exceeding 60C and for liquefied gases the cargo tank and the secondary barrier
spaces.
Zone 1Areas where an explosive-gas atmosphere will be periodically present during normal
operation. For example, spaces adjacent to andbelow the top of the cargo tanks carrying
crude oil, oilproducts etc. with a flash point not
Exceeding 60C.Spaces separatedby a single deck orbulkhead from zone 0 areas, also cargo
pump rooms and enclosed and semi-enclosed spaces in which pipes containing above cargoes
are located. Also areas on open deck within 3 metres of any cargo tank outlet, cargo valve,
cargo-pipe flange, cargo-pump room outlets, 6 metres radius from highpressure discharge
valves and 2.4 metres above deck
.Zone 2Areas where an explosive gas atmosphere is not present during normal operation and. if
present, for a short period of time for tankerscarrying products with a flash pointabove
60C.This is the only zone defined for the dry-cargo ships and for Ro/Ro spaces of ferries if
sufficiently ventilated. The explosive-gas atmosphere is considered not tobepresent during
normal operation.
Caution: Liquified natural gas (LNG) and the vapours from kerosine are heavier than air andany opening to a deck or lower space shall be subject to further study with respect to the
zoning. The gases are divided into the following groups:
- Group I: methane such as expected in coal mines
- Group II: General industrial gases and gases from combustible liquids and combustible
solids
- Group IIA: Propane
- Group IIB: Ethylene
- Group IIC: Hydrogen
Apart from the gas group, certified safe equipment shall also be selected on the basis of the
maximum surface temperature during operation. This surface temperature shallbe below the
ignition temperature of the gas emittedby the cargo as is stated in the cargo lists.Temperature classes and maximum surface temperatures are as follows:
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TI below 450C
T2 300C
T3 200C
T4 135C
T5 100C
T6 85C