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14/05/2024

Phase fail. The turning gear and the LO autofilter of the main engine do not start

Greetings! Today we have a problem with the turning gear and the LO autofilter of the main engine. During the preparation of the main engine, alarms were sent to the alarm monitoring system in the ECR indicating that some kind of problem had occurred with these mechanisms.

Phase fail. The turning gear and the LO autofilter of the main engine do not start

It is necessary to pay attention to the fact that problems with starters or motors occurred at the same time and perhaps they have something in common. On a ship, these systems are not connected to each other in any way.

After checking the 440V power supply that comes to the main starting contactor of the turning gear, it turned out that one phase was lost. It gets lost until the circuit breaker.

Electrical diagram of the turning gear device
Electrical diagram of the turning gear device
Starter panel of the turning gearStarter panel of the turning gear
Starter panel of the turning gear

Usually, when one phase is lost, the motor is noisy (humming) and may turn over, thermal protection trips the control circuit, fuses may blow, the circuit breaker may trip, or does it all at once.

Electrical diagram of the LO autofilter

Electrical diagram of the LO autofilter

Electrical diagram of the LO autofilter
Electrical diagram of the LO autofilter

As a result, the problem was discovered in the 440V distribution board, where one busbar lost its fastening (as a result of increased vibration), burned and thus the power section lost one phase.

Distribution board 440V
Distribution board 440V
Problem busbar
Problem busbar
440V distribution board diagram
440V distribution board diagram

In this case, only the turning gear and LO autofilter of the main engine lost phase; other units of this switchboard remained in normal operating condition.

Phase Loss
Phase Loss
Normal phase 440V
Normal phase 440V

As a result, the 440V switchboard was restored and the turning gear and LO autofilter were put into normal operation.

In this article I want to focus on the fact that two different systems were found with the same problems. What is also confusing is that both systems belong to the main engine and the problem occurred during its preparation.

It is always very important for a marine electrical engineer to be able to identify the common cause of a breakdown that concerns several mechanisms or systems in order to quickly detect and eliminate the problem. Ask yourself: “What do these systems or mechanisms have in common?”

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