How does an electric fan motor work?
Electric fans are also one of the most important household appliances in summer, which can bring some comfort to our lives. One of the important components of the fan is the motor. Do we know what the motor of the fan is? We may not pay much attention to these matters. Now let's introduce the working principle of electric fan motor? Precautions for the purchase of electric fan motors?
Working principle of electric fan motor
1. Although the motor fan has high reliability, it is still a mechanical device. When used for a long time, its speed may drop or even stop. Therefore, real-time monitoring of the running status of the fan is convenient to find problems in time. Using the alarm sensor, an alarm signal can be given when the fan speed is lower than a certain threshold value, and the speed signal output can realize the real-time monitoring of the fan speed.
2. The alarm signal output from the fan circuit has two states: "high level" and "low level". The meanings represented by the two levels are generally in accordance with the positive logic system. Flat" means "normal". The speed signal output from the fan circuit is usually in the form of pulses, and each wave head indicates that the fan has rotated one circle. Such a signal can be directly provided to the host through the data bus for display.
3. The speed signal output by some fans is not the real speed of the fan, but a multiple of the speed. For example, 2, 4 or 6 pulses are generated per revolution, which must be processed to reflect the real speed signal of the fan. To tell if the fan speed is the real speed or a multiple, measure the actual speed with a tachometer and compare it with the displayed data.
4. The speed measurement signal of the fan is generally output from the three-lead plug. The yellow and black of the three leads are +12V power supply and grounding respectively, and the other color line is the speed signal output line. It should be noted that the third lead of some three-lead fans is not the speed measurement signal output line, but the speed control signal line, through which the speed control signal is input to the fan motor.
Precautions for the purchase of electric fan motors
1. Look at random files
The motor fan is randomly equipped with the instruction manual, product certificate, electrical circuit diagram and packing list. It is necessary to check the packing list and check the parts.
2. Look at the shape of the motor fan
Carefully check the motor fan grille and fan blades for obvious deformation. Rotating the fan blades should be light and flexible, and should not always stop at the same position.
3. Look at the startup performance
The starting performance is an important quality indicator of the motor fan. During the inspection, in the slow gear, when the rated voltage of the power supply is 85%, the motor fan should be able to start from a standstill and run normally. The shorter the time required for a motor fan to start to normal operation, the better the start performance of the motor fan .
4. Look at the speed regulation performance
After the power is turned on, there should be no abnormal noise in the mechanical transmission part of the fan. When the electric fan is running at high, medium and low speed, the motor and fan blades should be stable, with low vibration and low noise. The motor fan should shake its head and stop quickly, without interruption, stagnation and shaking.
5, to see if there is leakage
After the motor fan is charged, if you feel numbness when you touch it, use a test pen to test it. The test pen also has a light-emitting display, which can determine that the casing is leaking and cannot be used.
6. Look at the continuous operation of the motor fan
After the electric fan runs continuously, if the surface of the machine head casing is hot, it means that the temperature is too high and cannot be used. Under normal circumstances, the surface temperature of the machine head shell is below 50 ℃, and there should be no hot feeling.
