This is program seven of video tells series on practical marine electrical
knowledge the series is made up of eight programs this program lists the minimum
preparation procedures to be carried out on board ship in anticipation of an
electrical survey the International Maritime Organization and the
International Electrotechnical convention have several codes and
regulations relating to safe electrical practice these must be studied and
adhered to when carrying out any work on marine electrical systems there are many
system variations around so it is most important that you become familiar with
the components of the electrical system and the layout of the main switchboard
immediately you join a ship pay particular attention to the layout of
the emergency switchboard this study will pay dividends during a blackout or
when troubleshooting the cause of a major breakdown
now we must emphasize Electrical Safety the golden rule is before any work is
done on an electrical installation first isolate the circuit by removing the
supply fuses or locking the circuit breaker in the open position so that the
circuit cannot be energized accidentally then post a warning sign to alert others
that the circuit is being worked on then prove the circuit dead with a
voltmeter or an approved line tester a switchboard can never be considered dead
unless all AC generators connected to it are stopped locked off and all other
supplies are disconnected these points can never be emphasized strongly enough
the electrical rescue procedure is described in program one of this series
the ship's electrical equipment is inspected and tested during the complete
engine survey which is carried out every four years the electrical survey
guidance given in this program is based on the periodical survey regulations of
a classification Society first prepare a complete list of all insulation
resistance reading or AC generators motor power and light
circuits and main feeder cables with special attention to cables in hazardous
areas when you take insulation resistance readings of AC generator
windings this should be done when the AC generator is still hot
after running on load a reading of 1 megohm is an acceptable value for a 440
volt AC generator winding for the lower voltage rotor winding this can be not
0.5 Megan
clean all AC generator windings and check your instruments and controls for
AC generator synchronizing the survey will require that the AC generators
respond correctly to controls and load changes and that they show a stable
operation when running in parallel
test the automatic startup system for the emergency AC generator ensuring that
the system is operational within the regulation 45 seconds after a mains
failure connect the emergency AC generator to the switchboard with a load
such as the motor for a firefighting pump when you're ready to connect the AC
generator to the emergency switchboard do remember that the AC generator
breaker cannot be closed until the tie breaker from the main switchboard is
opened check that the board is dead then check all internal connections in the
main as well as in the emergency switchboard ensuring that all
connections are clean and dry any connections which do not prove tight
enough must be remade and rechecked
all main busbar and auxiliary connections throughout the boards should
be checked for loose joints buzz bar supports should be examined for surface
tracking and possible damage to the insulation material
check that all circuit breakers will pass a visual test paying particular
attention to the condition of main arcing and auxiliary contacts all
internal wiring must be sound and the mechanical linkage is free of wear and
stress arc chutes must be clean free of arc debris and correctly aligned look
for signs of wear misalignment or overheating
check the reverse power relay and the preferential trip relay for correct
timing and operation consult the ship's manual for correct settings
check and clean all starters as the surveyor will probably conduct spot
checks on starters he will look for badly burned or misaligned contacts
loose connections worn pigtails on moving contacts and signs of overheating
on coils transformers and resistors
check that all motor stator windings are clean and dry the surveyor may take one
or two ventilating grids off to inspect the windings for cleanliness and dryness
this applies particularly to drip proof weather proof and deck watertight
enclosures the surveyor will want to look for the ingress of water or oil
check and test the steering gear over current alarms as these do not trip the
system but merely warn if over current conditions arise check all main and
alternative electric supplies including the changeover switching for electric
control from the bridge and for autopilot check the rudder position
indicator
check the emergency battery condition and ensure that the charger functions
efficiently the battery tops must be clean with no corrosion of the terminals
and connections the battery electrolyte should be at its correct level and have
the proper value of specific gravity checked by a hydrometer check the
navigation light panel and prove the alarm system to be working the surveyor
may remove a fuse to check if the appropriate alarm is operating correctly
check all exterior light fittings replace any burned-out lamps
on exterior floodlight fittings check the flexible cable connections for any
sign of damage to the cable insulation
any temporary cabling which is to be in use for some time has to be made
permanent the cables must be laid and clipped
safely and securely in the appropriate support trays
remember that cables for intrinsically safe circuitry must be laid separately
from others of different classification and clearly marked as such if your ship
is classified for unattended machinery space we so called UMS operation the
electrical survey will be extended to include all alarms fire detection
controls and failsafe installations all alarms associated with the main engine
auxiliary machines lubrication and cooling are to be tested for correct
function by operating the sensor switches by hand or simulating the
switch action under the expected alarm conditions
the duplicate builds metal alarms must be proved to work to the satisfaction of
the surveil check that all required electrical spares are available for
inspection in the electrical spare store
they must be correctly stored and in good condition
this concludes the subject for program seven here we have recommended a list of
jobs which should be carried out in preparation for an electrical survey we
recommend that you watch this program again and that you consult the book
practical marine electrical knowledge which accompanies this series and will
allow you to study certain aspects in greater detail finally here's a list of
contents for all the programs in the series