Frequency converter distribution motor problem.

There is an independent fan at the end of the variable frequency motor. The independent fan can dissipate heat to the motor. Ordinary motors dissipate heat by relying on a fan blade on the extended shaft at the end of the motor, which is the same shaft. If the frequency converter is used to lower the frequency, the motor speed will be reduced, and the fan blades on the extended shaft will rotate at a low speed. The heat dissipation effect is not good, and it is easy to burn the motor.

1. The main difference between a variable frequency motor and an ordinary motor is that the variable frequency motor considers the problem of motor fan cooling, and specially installs a fan motor running at power frequency to ensure the effectiveness of heat dissipation when the motor is running at low frequency. The relationship between energy saving is not direct. When using a frequency converter for ordinary motors, you only need to control the speed range of the operation. The price is not much different.

Ordinary motors can also be used with variable frequency, but they require a speed adjustment range.

The motors of our company's variable frequency equipment are generally ordinary motors, and there are only 5 special variable frequency motors. From a macro perspective: 1. The rear fan of the variable frequency motor is specially powered, but the ordinary motor is not. 2. Ordinary motors produce greater noise and vibration than variable frequency motors. ； And the temperature rise is higher. There is no big difference from the control point of view.

Adjustment below the power frequency can be used. An independent fan is added according to the situation. Generally, the inverter is selected according to the capacity of the 4-pole motor. If it is a 2-pole motor, choose an inverter with a larger capacity.

I haven't studied variable frequency motors specifically. But I have encountered some problems in my daily work. There are only two that are more impressive now. 1. The frequency of ordinary motors should not exceed 50HZ. Otherwise, it is easy to burn the motor. A variable frequency motor seems to be better. 2. Ordinary motor frequency conversion. It is best not to run at ultra-low frequency. At this time, the fan will also run at low frequency. The heat dissipation effect is not good. Generally speaking, it is easy to burn the motor. Common industrial fan and pump loads rarely include the above two. (Or try to avoid it), in this case, ordinary motors are still very practical to be transformed with frequency conversion! ~! :lol

In fact, none of the previous ones are comprehensive and accurate. 1. Variable frequency motors do not necessarily need to be equipped with an attached fan. The biggest difference between them and ordinary motors is their better heat resistance, which can ensure normal operation of the motor at low frequencies.； 2. If your application runs at 25-55HZ, you can choose an ordinary motor instead.

After reading the above answers, I feel a little impulsive. I really can’t sit back and ignore it. I would like to share my views, for reference only! 1) The biggest difference between ordinary motors and variable frequency motors is the difference in design ideas. Ordinary motors are designed according to constant frequency and constant voltage, and cannot fully adapt to the requirements of variable frequency speed regulation. In terms of electromagnetic design, for ordinary motors, the main performance parameters considered during design are overload capacity, starting performance, efficiency and power factor. As for variable frequency motors, since the critical slip is inversely proportional to the power supply frequency, it can be started directly when the critical slip is close to 1. Therefore, overload capacity and starting performance no longer need to be considered too much. The key issue to be solved is how to improve the motor's adaptability to non-sinusoidal power supplies. There are many ways to solve it. ； When designing the structure, the variable frequency motor mainly considers the impact of non-sinusoidal power supply characteristics on the insulation structure, vibration, noise cooling method, etc. of the variable frequency motor. The structural treatment is also very different from that of ordinary motors. 2) The second thing you see is that when ordinary motors are used for variable frequency, independent fans are often added, and they mainly run below the base frequency. Because ordinary motors are used for variable frequency, their efficiency is low, their temperatures rise, and their anti-harmonic capabilities are relatively weak, so they need to strengthen their heat dissipation capabilities. On the other hand, ordinary motors generate serious heat below 10Hz when running at low speeds and are not suitable for running at low speeds. When the motor runs above the base frequency, the heat generation is much more serious than when it is below. The most important thing is that it is easy to breakdown, so it is generally run below the base frequency. 3) Regarding the use of frequency converters to save energy, it is not energy-saving when using frequency converters. Some are just for speed regulation. Energy-saving is mainly used in industries such as water pumps and fans. Because its speed and power are related to the third power, the energy-saving effect is obvious.

Ordinary motors can also be used with variable frequency, but the speed regulation range is required. When selecting the type, the power of the frequency converter is one gear larger than the motor for better matching.

The biggest difference between variable frequency motors and ordinary induction motors is that their magnetic circuit system and insulation structure are specially designed to meet the needs of PWM frequency conversion technology. You can check the related* * Standard and variable frequency motor design manual. Some inverter manufacturers say that ordinary cage motors can be connected. From a technical point of view, there is no problem, but the service life of the motor * * Shortening, for example, a motor usually used for 20 years can be used for up to 5 years when connected to an inverter.

@9th floor, professional! :handshake

Read the experience of the masters and learn from it* . Thanks

When ordinary motors use frequency converters, it is easy for the voltage of the frequency converter to superimpose and the motor to burn out. However, faults are generally difficult to find on the coils and can only be detected by testing, and the manufacturer does not provide warranty. We have seen 3 of these this year, and the manufacturer doesn't care. From Nanyang.

Agree with the 9th floor. On the surface, the variable frequency motor just has an additional independent fan. In fact, its structure and insulation type are different, otherwise it would not be 50% more expensive.