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Main Engine RPM pickup sensor failure

ME encounter alarm during arrival at Rotterdam, the alarm ME RPM signal fail from pulse sensor. When ME reached full ahead, after few minutes suddenly the ME RPM signal fail and ME over speed alarm occurred but the engine is at normal speed. The ME RPM signal fail could not reset.

During stay at port checked the pulse sensor and cleaned the fly wheel. The fly wheel found grease and slight oil in the teeth of the fly wheel. Checked the terminal box of pulse sensor and found little amount of oil inside the terminal box no sign of burn or short circuited observed.

During departure / piloting stage no alarm encounter any alarm in ME system and after 24 hours the ME RPM signal fail alarm occurred again. The ME is in normal speed. We checked the terminal box of pulse sensor we found that the pulse sensor the LED light is not blinking the LED light ( RED ) is steady only . it means the pulse sensor is not sensing the fly wheel. Once the vessel arrive at discharging port we will check the distance or might be the pickup sensor is defective. Kindly advice.

12 Aug '19, 09:38

Aug. 12, 2019, 9:38 a.m.
KnowledgeBase's gravatar image


Answer:

From the previous experience with RPM pickup sensors, causes of failure listed below were experienced:

  1. Sensor is dirty - already cleaned by crew
  2. The clearance between sensor and flywheel is incorrect. Often, due to vibration, the sensor holding nuts or the terminal box holding nuts/bolts may get loosen - to be checked and adjusted, as crew planned already.
  3. The wiring in the terminal boxes may get loosen due to vibration. As the fault appears randomly, this may be the cause. - Wiring all the way from the sensor to ME control unit to be checked for loosen terminals.
  4. Faulty sensor - to be replaced.
  5. Current leak due to the grounded sensor or it's wiring. Appears along with the earth fault. If no 24V earth fault observed this is not the case. If earth fault confirmed - the sensor wiring to be inspected for wiring with defective insulation, sensor replaced.

Hope these will help

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12 Aug '19, 09:39

Aug. 12, 2019, 9:39 a.m.
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