Crane Failure and Troubleshooting 4: Electric Control Article

In the crane use process, mechanical parts, components, electrical control and hydraulic system components will be worn and lead to failure. Possible causes for the same fault are not one to one corresponding relationship. So in order to make serious analysis of fault and accurately find the real cause of the malfunction, and take elimination method corresponding to the exclusion of the fault point to restore the technical performance.

Crane electric control article failure and troubleshooting

A. When the knife switch close, the fuse of the control circuit is burnt out failure and reason:

The cause:

• The phase of the control circuit connect ground
• Solving method:
• Use multimeter to check location of earthing

B. After the controller of one organization move, overcurrent relay work failure and reason:

• The cause:
• The setting value of the motor overcurrent relay is not in conformity with the requirement.

Solving method:

• Adjust the setting value of the overcurrent relay (I = 2.25 ~ 2.5 rated current)

C. After the main contactor close, the fuse the introduction line is burnt out failure and reason:

The cause:

• The phase of the control circuit connect ground
• Solving method:
• Use multimeter to check location of earthing

D. After the controller close, the motor does not rotate failure and reason:

The causes:

• 1. One phase power turn off and the motor has noise
• 2. Rotor circuit disconnect
• 3. Electric line has no voltage
• 4. the contactor of controller doesn’t contact
• 5. Collector brush has failure
• 6. Brake has failure and it can’t be loosened

Solving method:

• 1. Find out the damage point, then connect the line
• 2. Find out the damage point, then connect the line
• 3. Find out the damage point, then connect the line
• 4. Maintain controller
• 5. Maintain controller

6. Maintain brake

E. After the controller close, the motor can only rotate in one direction failure and reason:

The causes:

• 1. Controller reverse contact is not good or rotating mechanism has failure
• 2. The fault of power distribution line
• 3. The working mechanism moves to the extreme point, and the limit switch is pressed.
• 4. limit switch has failure

Solving method:

• 1. Maintain controller and adjust the contact
• 2. Find out and eliminate the faults by using the method of short connection
• 3. Only operate in one direction
• 4. Check the limit switch, and eliminate the failure.

F. After the end limit switch act, the main contactor is not released failure and reason:

The causes:

• 1. The end limit switch circuit has circuit break
• 2. The connecting line to controller is disorder

Solving method:

• 1. Maintenance and eliminate circuit break
• 2. Correct wiring errors

G. After the controller works, the main contactor is not released failure and reason:

The causes:

• 1. Location machine has failure
• 2. The contact has failure

Solving method:

• 1. Eliminate faults
• 2. Adjust the position of the contact

H. In the running controller does not move failure and reason:
The causes:

• Contact burn and bond
• Solving method:
• Clean contact by file

I. Generator doesn’t excite electromagnetism failure and reason:

The causes:

• 1. Excitation circuit has circuit break
• 2. The rotate direction of the generator is opposite

Solving method:

• 1. Check the excitation circuit
• 2. Transpose the two phase connection wire of the drive circuit rotor

J. After power cut off, the contactor does not fall off failure and reason:
The causes:

• 1. Ground wire has break circuit in the control circuit
• 2. Contactor contact is welded, it continues to supply the main circuit power

Solving method:

• 1. Check the earthing or short circuit and troubleshooting
• 2. Filing burnt contact and make good contact

Related information on lifting crane failure and troubleshooting

Crane Failure and Troubleshooting 1：Part Article
Crane Failure and Troubleshooting 2: Unit Article
Crane Failure and Troubleshooting 3: Electrical Equipment Article 
Crane Failure and Troubleshooting 4: Electric Control Article