Author: Wu Xinsheng, senior engineer

(Nanjing Avis Transmission Technology Co., Ltd.)

The misalignment of the fan refers to the degree of deflection or offset between the axis of the rotor of the fan and the motor and the center line of the bearing. The fan and the motor are connected by a coupling to transmit motion and torque.

Fan misalignment is a common cause of fan failure. A misaligned gearbox and generator will cause mechanical vibration, aggravate bearing wear and shaft deflection, causing great harm to the smooth operation of the wind turbine. Coupling misalignment is the main component of fan misalignment.

Main causes of coupling misalignment

1, the installation error of the coupling, the thermal expansion under working conditions and the deformation after load will cause misalignment.

2, generator and gearbox assembly and long-term operation wear. Large motors have high requirements for dynamic balance themselves. Due to various factors during long-term operation, the base fastening bolts may become slightly loose, and the dynamic balance of the motor itself may be damaged, resulting in misalignment.

Three forms of coupling misalignment

A. Two axes are parallel, two axes are not concentric, and radial displacement;

B. The two weeks are not parallel, the two axes are concentric and angularly offset;

C. The two weeks are not parallel, the two axes are not concentric, and there is a comprehensive offset.

The dangers of coupling misalignment

When the fan is misaligned, it will aggravate the wear of the gearbox and generator bearings and the deflection deformation of the shaft. The increased stress on the rotor and the additional force on the bearing will lead to abnormal vibration of the fan and early damage to the bearing, causing great damage.

Coupling misalignment treatment

First, find the level of the fan main shaft, and rotate the impeller to ensure that the level deviation of the fan main shaft at each point is within the range; then find the alignment of the fan and motor coupling, usually using a dial indicator to detect the runout at four points to ensure that the runout at the four points is within the technical range.

At present, misalignment is usually solved by laser alignment. The specific operations are as follows:

The installation diagram of the alignment instrument is as follows:

The measurement data is shown as follows:

General requirements for alignment:

Vertical angle deviation M≤0.05/100

Vertical parallel deviation H≤0.05

Horizontal angle deviation M≤0.05/100

Horizontal parallel deviation H≤0.05

Please refer to the following table for specific requirements:

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