21/07/2023

Motor Fault on the crane. Troubleshooting

Greetings! Today we got a "Motor Fault" error on the cargo crane and the crane doesn't want to start. In the article we will consider the main actions of ETO when searching for and eliminating this malfunction.

Motor Fault on the Crane
Motor Fault on the Crane

The problem is quite large-scale and it can be anything related primarily to electric drives of both the main and auxiliary mechanisms of the crane. There was also a short-term accompanying signal in the ECR on AMS "low insulation 440V", which further narrowed the circle of my search.

The instruction offers several options for finding and eliminating this error.

Troubleshooting motor faultTroubleshooting motor fault
Troubleshooting motor fault

As you can see from the instructions, first of all, you need to check the line of the main electric drive, the thermal and overcurrent relay, the magnetic contactor of the main electric motor. PLC modules at the same time help us to find the problem via LED lights on the modules.

Crane PLC
Crane PLC

If we look at drawings, we can see that the Motor fault alarm associated with PLC module and is a combination of all alarms for electric drives.

Motor fault alarm
Motor fault alarm

In my case, the problem turned out to be in one of the fans for cooling the oil of the hydraulic system of the crane. The thermal relay of the Oil cooler motor was tripped.

Thermal protection of the motor
Thermal protection of the motor
Contact of thermal relay and motor error
Contact of thermal relay and motor fault

With the help of a portable megaohmmeter, I made sure that the resistance of the motor insulation relative to the case is about 0 MĪ©, and the next step was to replace the electric motor with a working one with good insulation.

The problem turned out to be in the motor, in which the insulation decreased and the heat began to trip it out. The problem could be also in the jamming of the fan impeller, motor bearings, poor air flow of the oil cooler, and also in the electrical circuit (malfunction of the breaker, contactor, thermal relay).

Motor insulation resistance
Motor insulation resistance
Hydraulic Oil Cooler of the Crane
Hydraulic Oil Cooler of the Crane
Installing a new motor
Installing a new motor

After that, I reseted the thermal protection using the Reset button, restarted the cargo crane and made sure that the cooling fan was working properly.

Thermal relay reset button
Thermal relay reset button

As we can see, it was Troubleshooting from the manufacturer that helped with this problem. Here, the drawings play a secondary role and do not explain what kind of error occurred. The general MOTOR FAULT alarm went out, and only after checking the circuits of all motors was the cause of this signal found.

Primitive Troubleshooting
Primitive Troubleshooting

On vessels, this troubleshooting method is most often found in the instructions for automation systems on PLC modules.

Crane Model: DMC DDKC-3026-00 (Dongnam Marine Crane)

Also read other articles about DMC cargo cranes:

  1. Problems with cargo cranes. Some problems with cargo cranes that occur on the ship
  2. The cargo crane does not slew. Troubleshooting
  3. The crane hook goes up slowly. The cargo crane is not working. Troubleshooting
  4. PLC failure. The cargo crane does not start. Troubleshooting
  5. The crane jib is luffing down under its own weight. Troubleshooting

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