General shipboard testing


General shipboard testing

After the Factury Acceptance Tests are completed to satisfac­tion, the equipment has to be installed on board. When com­pleted, a new series of tests has to be carried out: The Harbour Acceptance Test, or HAT.

Before this testing can be car­ried out, cables, pipes, safety systems, such as firedetec­tion, bilgealarm, etc, have to be ready and have to be test­ed. This is in fact pre-testing, and part of the HAT. There is an overlap with the actual HAT, which is carried out when all systems and equipment is sup­posed to be ready.
Before a new installation is put into service, the following tests are to be carried out. These tests are in addition to any acceptance tests which may have been carried out at the manufacturer's .

   1. Insulation resistance

The insulation resistance of all sys­tems and electrical equipment has to be measured using a direct cur­rent insulation tester, between: a. connected current carrying parts b. as far as reasonably practicable all current carrying parts of dif­ferent polarity or phase.

The installation may be subdivided and equipment may be disconnect­ed if initial tests produce resistance values lower than the required re­sistances.

   2. Earth conductors

Tests are to be carried out to verify the effectiveness of the earth con­tinuity conductor and the earthing of non-current carrying exposed metal parts of electrical equipment and cables.

   3.  Generators

     Tests are required to demonstrate satisfactory performance of each generator and engine by means of a test run at full rated load and at 110% overload for at least 15 min­utes. Engine temperatures should stabilize and not exceed the maxi­mum figures as determined by the manufacturer.

Example of part of Megger list

General shipboard testing

Minimum test voltage and insulation resistance M_a

General shipboard testing

   4.  Switchboards

     During the full load tests, the tem­peratures of joints, connections, cir­cuit breakers, bus-bars and fuses have to be monitored and may not exceed the maximum values. For cables with XLPE insulation this value should be below 85°C. Bus-bars in switchboards may reach 95 °C.

   5. Synchronising equipment

During functional tests the operation of engine governors, synchronizing devices, overspeed trips, reverse­current relays, reverse-power and over-current trips and other safety devices must be demonstrated. Gen­erators with a rating of more than 1500kVA must also be protected by a differential protection system, show­ing a possible current leakage.

   6.  Automatic Voltage Regulator

The voltage regulator of each gen­erator has to be tested by opening its breaker when the generator is run­ning at full load and also when start­ing the largest motor which is con­nected to the system.

Also the speed governor has to be tested by opening the circuit breaker at full load. This is not to result in overspeed trip. The minimum speed of a diesel generator has to be veri­fied when starting the largest electric motor on board.

   7. Parallel operation

Parallel operation and kW and kVA load sharing of all generators capable of being operated in parallel mode, at all loads up to normal working load, has to be tested.

   8. Functional test

     Essential equipment must be operat­ed under service conditions, though not necessarily at full load or simul­taneously, for a sufficient length of time to demonstrate that the tem­peratures stabilize and equipment does not overheat.

   9. Safety systems

Fire, crew and passenger and ship safety systems must be tested for correct functioning.

General shipboard testing
General shipboard testing
General shipboard testing

High Voltage test voltage depends on the nominal voltage of the system as in the following table:

General shipboard testing

   10. General alarm systems

On completion of the general emer­gency alarm system and the public address system tests, the surveyor has to be provided with two copies of the test schedule, detailing the measured sound pressure levels. Such schedules are to be signed by the surveyor and the builder.

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