EARTH FAULT mmd oral

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  1. 440v Earth fault is considered as a emergency onboard 
  2. For some ships have trips for 440v earth faults.
  3. For 3000v and  above its mandatory to to fit the trip protection against earth fault.


How to find the earth fault in 440v?

  • When you hear the earth fault alarm, inform the electrical officer if he is board.
  • Check the alarm, sometimes false alarm will rise. Test the alarm using test button,
  • Or if we have integrated automation system, we can check by  software.
  • Now isolate the whole 440v system (but its not possible to isolate 440v, is because some machinery can not we isolate like steering gear & lub oil pumps. 
  • So we can use standby options. 
  • Keep checking on the system one by one, we will find the earth fault machinery.

HOW WILL YOU FIND THE EARTH FAULT IN 220 V?
  •  For 220 v earth fault is not consider the major emergency onboard. But any way we have to find the faulty lighting circuit.
  • First of all check the alarm which is working properly or not using test button.
  • Then isolate the whole lighting system.check the it one by one.using breaker.
  • For after finding the the particular area of earth fault in 220v.
  • We will check the particular section one by ine circuits.
  • Finally we will found the earth fault .

Eart fault detected why we are isolating  system?
  •  To Prevent from over heating 
  • To prevent from  short circuit.


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