Finding a earth fault on 440v and 220v circuit on board ship
Whenever there is an Earth fault alarm immediately inform the electrical officer (if he is on board).
The first action is to check the trueness of the alarm usually there will be a test button when pressed reset the alarm and rechecks the condition of the earth fault.
If the ship is having IAS (Integrated Automation system). Check on the computer in the list of event after which the alarm has activated.
If IAS facility is not available, there is only one option of Isolating each and every machine in the 440 v circuit and Checking whether the Earth fault indication returns to normal.
Isolation of all machinery which operates on 440 v is not always possible, certain critical equipment like steering gear and Lube oil pumps can not be isolated. For when the ships underway However changeover can be done from running machinery to the stand by one thus the earth fault can be found.
Finding earth fault on 220v circuit
It is comparatively difficult than the 440 v circuit. The main reason is being the lighting circuits found all around the vessel. However, any Earth fault Alarm concerning a 220v circuit is usually treated as important but not an emergency when a 220V earth fault alarm Sounds, as said earlier the trueness of alarm is checked by pressing the test button and then the investigation can be started on each and every 200 v circuit.
Example: Earth faults alarm sounds on a 220v panel.
- Check the trueness of the alarm by pressing the test button.
- Isolate the complete group start panel for a lighting division by one,
- Check the Earth fault Indication for status (Still/full/Normal),
- If faulty, put on the breaker, which is put off earlier, isolate other group Start one by one, and check for alarm condition.
- When any switch is turned off thus the condition becomes normal when the lighting circuit is marked and inspection is done on the particular light for abnormalities.
- Ingress of moisture is most common for an earth fault.
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