Look at the random documents. The random documents of each fan include the use instructions, product certificates, electrical circuit diagrams and packing lists. When purchasing, check the quantity and quality of parts and components according to the packing list.

See if the mesh cover and fan blade have obvious deformation: on the assembled electric fan mesh cover, point a pen at the highest point of a fan blade, slowly move the fan blade, the corresponding points of several other fan blades should be very close to the tip of the pen, then rotate the fan blade, pay attention to whether the rotation is light and flexible, and can stop at any position.

See if the control mechanism is flexible: the control mechanism includes speed control switch, timing knob, shaking head switch, lighting switch, etc. These control mechanisms should be flexible in operation and reliable in contact. For speed control gears, it is not allowed to have two gears connected at the same time or one gear can not be pressed down. Press the stop button, and the speed block keys should be reset normally.

Look at the performance of the movable part: the fan head is flexible in pitch and pitch, and the lock is firm. It can be adjusted to the maximum pitch angle or shake the head to the final position. The net cover can not touch the fan prop. When the fan is running, the stability is good, it can not be tilted, and the shaking angle should not be less than 60-80 degrees.

Look at start-up performance: Start-up performance is an important quality index of electric fans. When checking, the fan should be set at the micro-fan, and when the rated voltage of the power supply is 85%, that is to say, when the 220 volt voltage is reduced to 187 volt by the voltage regulator, the fan should be able to start from static state and run normally. The shorter the time it takes for a fan to start to run normally, the better the start-up performance of the fan motor will be.

Look at the performance of operation and speed regulation: after power-on, the shaking head switch will rotate several times to check whether it is out of order or assembly is too tight. In this process, the mechanical transmission part of the fan should not have abnormal noise. When the electric fan runs in small, medium and strong wind, the motor and the fan blade should be stable, less vibration and low noise. Fan shaking head and stopping should be agile, without intermittence, stagnation and jitter. The speed difference of each block should be obvious. The bigger the angle of air supply, the better. When the fan stops running, the axial clearance of the rotating shaft does not exceed 0.5 cm. If the clearance is too large, it will cause axial movement and impact sound when running.

See if leakage: After the fan is powered on, if the hand touches strong hemp inductance, test with a test pen, the test pen will also display light, which can determine the leakage of the housing, not to be selected.