If IAS facility is not available, there is only one option of isolating each and every machinery in the 440 V circuit and check whether the earth fault indication returns back to normal.
If the ship is having IAS (Integrated Automation System), check on the computer in the list of events after which the alarm has activated. Usually there will be a test button which when pressed, resets the alarm and rechecks the condition of the earth fault. First action is to check the trueness of the alarm. Whenever there is an earth fault alarm, immediately inform to electrical officer (if he is on board). However, attention should be paid at the next earliest opportunity. Any earth fault on 220V or any low voltage lighting circuit can be considered as important but need not require immediate attention. Any earth fault on a 440V system is considered to be a serious trouble and immediate action is required to identify the faulty circuit. Conventional ships which operate on 3 Phase, 440V, have earth fault indicators installed on all three phases. The seriousness of the action to be taken on an Earth Fault depends on the part of the electrical system it affects. However when the operating voltage exceeds 3000V, it is mandatory to have a protection system which isolates when a machinery suffers an earth fault. Some ships which operate at 440 V do not have any trip devices attached for a single earth fault. Earth fault is considered very critical on board a ship.
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