【Weekly Topic】Discussion on frequency conversion upgrades
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In the current economic downturn, many companies are seeking to reduce costs by implementing variable frequency modifications based on the operating conditions of their production systems, thereby enabling them to \"survive and maintain stable development\". However, in frequency conversion upgrades, it sometimes happens that only the frequency converter is added without replacing the motor. This leads to this week’s topic: This week’s topic – What aspects need to be taken into consideration in production operations when carrying out upgrades that involve only adding a frequency converter without replacing the motor? What are the differences between variable-frequency motors and ordinary motors when used in combination with frequency converters? Everyone is welcome to actively participate in the discussion! 【Collection of Essential Knowledge for the Mechanical Forum】http://bbs.hcbbs.com/thread-1389197-1-1.html Topics for each week and daily questions are being sought (prizes available for participation) http://bbs.hcbbs.com/thread-1373282-1-1.html Summary post of weekly topics: http://bbs.hcbbs.com/thread-1404940-1-1.html Starting today, the Mechanical Forum is bringing wealth to all its members http://bbs.hcbbs.com/thread-1489563-1-1.html Go and claim your wealth now – the distribution has begun!
When a conventional motor is equipped with an inverter, attention must be paid to heat dissipation. Especially at low frequencies, such motors do not have dedicated fans; instead, they rely on the rotation of the motor itself to drive the blades at the back and generate airflow. At low frequencies, the rotation slows down, and the blades are unable to produce enough airflow, which leads to overheating of the motor.
Indeed, as the original poster said, in the case of only adding an inverter without replacing the motor, what’s the problem with that? On the other hand, the investment in frequency conversion will increase significantly; not everything needs to be upgraded to use frequency conversion, and choices need to be made.
There are mainly three differences between ordinary motors and variable-frequency motors: 1. The cooling systems are different； 2. Variable-frequency motors have improved the slot insulation; this is achieved by using stronger insulating materials as well as increasing the thickness of the slot insulation, in order to enhance their ability to withstand high-frequency voltages. 3. It increases the electromagnetic load. The operating point of a conventional motor is generally at the magnetic saturation point; when used for frequency conversion, it tends to saturate, resulting in high excitation currents. In contrast, variable-frequency motors are designed with an increased electromagnetic load, which prevents the magnetic circuit from saturating easily. Additionally, variable-frequency motors are generally divided into motors designed for constant torque applications, specialized motors with speed measurement devices used in feedback vector control, and medium-frequency motors, among others.
Add an inverter; pay attention to heat dissipation at low frequencies, install a separate fan, as inverter-driven motors have better insulation
What aspects need attention during production operation for modifications that involve only adding frequency converters without replacing the motors? What are the differences between variable-frequency motors and ordinary motors when used in combination with frequency converters? When using an inverter to drive a conventional motor, it is important to consider the actual operating frequency of the inverter. If this frequency is below 20 Hz and the motor operates at such a frequency for an extended period of time, a cooling system must be provided for the motor; otherwise, the motor may burn out ； In practical applications, the number of ordinary motors driven by frequency converters is far higher than that of variable-frequency motors driven by frequency converters. When a conventional motor is equipped with an inverter, attention must be paid to heat dissipation. Especially at low frequencies, such motors do not have dedicated fans; instead, they rely on the rotation of the motor itself to drive the blades at the back and generate airflow. At low frequencies, the rotation slows down, and the blades are unable to produce enough airflow, which leads to overheating of the motor.
When using an inverter to drive a conventional motor, it is important to consider the actual operating frequency of the inverter. If this frequency is below 20 Hz and the motor operates at such a frequency for an extended period of time, a cooling system must be provided for the motor; otherwise, the motor may burn out； In practical applications, the number of ordinary motors driven by frequency converters is far higher than that of variable-frequency motors driven by frequency converters. When a conventional motor is equipped with an inverter, attention must be paid to heat dissipation. Especially at low frequencies, such motors do not have dedicated fans; instead, they rely on the rotation of the motor itself to drive the blades at the back and generate airflow. At low frequencies, the rotation slows down, and the blades are unable to produce enough airflow, which leads to overheating of the motor.
There are the following issues: 1. The addition of an inverter is certainly intended for use at low frequencies in order to reduce energy consumption. Therefore, heat dissipation of the motor must be addressed when it operates at low frequencies, as the fan of a conventional motor slows down at such frequencies, resulting in poor heat dissipation； 2. Due to the addition of an inverter, harmonic voltages and currents cause losses in the rotor, leading to a decrease in power output as well as a faster increase in the motor’s temperature. 3. This can also result in vibration and noise in the motor
When installing a frequency converter on a regular motor, attention must be paid to heat dissipation; generally, the frequency should be kept above 60%, otherwise the motor will overheat.
How much electricity can be saved by installing an inverter, in kilowatt-hours? Is there a specific calculation method for controlling the frequency conversion at 60-70%?
Why, sometimes when the frequency converter is set to its maximum setting and both the pump’s head and flow rate reach their desired levels, is the pump’s current still only 70% of the rated value?