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Frequency inverter related questions and answers
Knowledge Base + 2024.01.25

A Variable Frequency Drive (VFD), also known as an inverter or adjustable speed drive, is a crucial component in modern industrial and commercial applications. VFDs are designed to control the speed and torque of electric motors by varying the frequency and voltage supplied to the motor. This dynamic control enables precise adjustment of motor speed, resulting in improved energy efficiency, enhanced process control, and reduced wear on mechanical components.

Key Features and Functions:

Speed Control: VFDs allow precise control over motor speed, enabling optimization for different operational requirements. This feature is particularly useful in applications where variable speeds are essential.

Energy Efficiency: By adjusting the motor speed to match the load requirements, VFDs contribute to significant energy savings. Motors operating at full speed even when not necessary can be inefficient and wasteful.

Soft Start and Stop: VFDs facilitate soft starting and stopping of motors, minimizing mechanical and electrical stress. This feature enhances equipment lifespan, reduces maintenance costs, and prevents sudden power surges.

Acceleration and Deceleration Control: VFDs provide smooth acceleration and deceleration, preventing abrupt changes in speed that could negatively impact equipment and processes.

Process Control: In industrial applications, VFDs play a crucial role in maintaining precise control over various processes. This is especially beneficial in scenarios where maintaining specific speeds and torques is critical.

Dynamic Braking: VFDs offer dynamic braking capabilities, allowing controlled and efficient stopping of motors. This is particularly useful in applications where rapid deceleration is required.

Torque Control: VFDs enable precise control over motor torque, ensuring optimal performance in applications with varying load conditions.

Remote Monitoring and Control: Many VFDs come equipped with communication interfaces that enable remote monitoring and control, providing operators with real-time insights into motor performance and operational parameters.

Comprehensive Protection: VFDs incorporate various protective features such as overcurrent protection, overvoltage protection, and fault detection mechanisms to safeguard the motor and associated equipment.


VFDs find extensive use in various industries, including manufacturing, HVAC systems, water treatment plants, conveyor systems, and more. Their versatility and energy-efficient operation make them indispensable for optimizing motor-driven processes in diverse applications.

In summary, Variable Frequency Drives are instrumental in enhancing the efficiency, reliability, and control of electric motor systems, contributing significantly to the advancement of modern industrial and commercial operations.

Frequency inverter related questions and answers

Q: The inverter circuit board can be used normally after blowing hot air with a fan. What could be the reason?

A: There could be several reasons for this situation:

  • Cold or loose solder joints on the circuit board, causing tin spots over time. Resoldering should fix this.

  • Leakage in electrolytic capacitors.

  • Poor thermal stability of the IC chip, although this is less likely.

Q: Schneider ATV-61 inverter does not have a start/stop button. Can this inverter only be started using buttons?

A: The Schneider ATV61 panel has up and down keys for adjusting frequency but cannot be used for starting or custom control. To start and stop, a Chinese panel needs to be purchased and connected to the inverter panel's mesh port.

Q: Huichuan MD280 5.5KW inverter frequently shows Err40 indicating overcurrent during power supply. Is this a circuit issue?

A: Overcurrent typically occurs after the inverter is started, not during power-up. If overcurrent occurs after power supply, consider it as a potential residual fault. Resetting using the reset function key may resolve the issue.

Q: How should the inverter board be maintained? Is it necessary to apply anti-corrosion paint?

A: Maintenance depends on the environment. Generally, inverters don't need anti-corrosion paint. If the environment is humid or dusty, applying a layer of glue after repair may be helpful. Anti-corrosion paint is not commonly applied unless the inverter has been exposed to harsh conditions.

Q: Leifeng 37KW inverter, pressing the start button increases frequency, but measured current is only a few amps. Is this normal?

A: If the measured current is on the input side, it's normal for a motor not under full load. Input current should be significantly less than output current. If measuring output current, for a 37KW motor, it should be around 74A under normal load.

Q: Will running a three-phase inverter with only two phases cause capacitor explosion?

A: Three-phase input inverters generally won't explode capacitors with only two phases. Output two-phase inverters would indicate a phase loss fault.

Q: Can a 380V inverter be used to start a 220V three-phase motor with the same power?

A: Yes, it can. Adjust the motor's voltage parameter from 380V to 220V, and set the inverter's maximum output voltage to 220V.

Q: Motor has leakage current during operation. Which parameter should be adjusted?

A: Inverters don't have a parameter for motor leakage. Check if the motor is properly grounded, and some inverters may have a ground current parameter to check.

Q: Inverter was normal before power-off, no running signal, but reports overcurrent. What could be the reason?

A: It could be an issue with the current transformers. If one of the three transformers outputs the highest current, it may trigger an overcurrent fault. Check the transformers.

Q: Weg VFD-B inverter, error code 13 indicates low-temperature alarm at 40 degrees. The environment is only 2 degrees. How to handle?

A: It could be a faulty temperature sensor on the heatsink. Check the displayed temperature on the panel. If it's significantly lower than the actual environment, the sensor might be faulty.

Q: What parameters should be set for a Delta VFD-B inverter, 2.2KW, connected to a 750W motor?

A: Set motor pole pairs, motor voltage, motor capacity, and the inverter's rated current percentage. Adjust the output torque to match the motor.

Q: Will connecting a lamp in series at the input of an inverter cause module damage?

A: It depends. Connecting a lamp in series is for charging purposes, ensuring it won't cause module damage. It's a common practice in repairing large inverters.

Q: Siemens inverter outputs balanced voltage, but the output current is unbalanced. Replacing the inverter solves the issue. What could be the reason?

A: The inverter has current compensation, and the issue might be with the current detection circuit inside the inverter.

Q: Siemens 430 inverter's output reactor temperature is high at 105 degrees. Is it an issue with the reactor?

A: Normally, the temperature should be around 60 degrees. High temperature could be due to a high carrier frequency setting or excessive output current.

Q: What are the main reasons for IGBT breakdown in an inverter?

A: Check for motor misconnection, input/output reversal, and whether it's a new or old inverter. If old, IGBT failure over 1-2 years is normal.

Q: ABB800 inverter frequently experiences control failure. Is it a problem with the inverter itself?

A: Check if the inverter is new or old. If new, ensure proper motor parameter and torque settings. If old, there might be an issue with the IGBT module or circuit board.

Q: 5.5kW inverter has difficulty starting under overload, and speed doesn't increase without a push. Which parameter needs adjustment?

A: Increase the inverter's output torque. All inverters have this parameter. Refer to the specific inverter's manual for details.

Q: How to adjust overcurrent in an inverter?

A: Overcurrent can occur during acceleration, constant speed, or deceleration. Investigate whether the issue is with the motor or the inverter. Check for high voltage at the current transformer output pin, as this may lead to overcurrent.

Q: Buying a new memory chip for VLT2800 and replacing it doesn't work. What could be the issue?

A: Simply buying and replacing the memory chip won't work. It needs the original data. Also, consider the version and compatibility of the chip with the inverter.

Q: In V/F mode, should the inverter self-learn motor parameters? What's the difference between learning and not learning? 

A: It depends on the brand of the inverter. For some brands, self-learning in V/F mode might not have much effect. V/F mode in inverters maintains constant torque. Generally, in V/F mode, it can be either with or without self-learning, but self-learning is recommended. However, in FOC mode, self-learning is necessary. After self-learning, the output torque at low frequencies is significantly enhanced. Without self-learning, low-frequency motors may experience insufficient torque.

Q: Emerson DC drive MP550A4, alarm HF04, data processing error, power processor has no communication. After replacing the mainboard, it works normally. What is the issue?

A:: The data processing error is likely related to the mainboard's database. Emerson CT mainboards are thin with a display digital tube on top. Check if it's this type of mainboard, and if the database on top is faulty, replacing it with a new one should resolve the issue.

Q: Mitsubishi F700 reports E6 error. What is the problem? The manual states CPU communication abnormality.

A: Check if the panel's crystal head is dirty, causing poor contact. Remove the panel, clean the crystal head, and clean the mesh. If it's a CPU communication abnormality, it should report E7, not E6. E6 is not a communication abnormality; E7 indicates an issue with the wires connecting the mainboard to the baseboard.

Q: Occasionally, the inverter struggles to start with a load, and the frequency doesn't go beyond around 7Hz. What could be the problem?

A: The inverter struggling to start occasionally may be due to a low output torque. If the inverter is set to 50Hz but only reaches 7Hz, it indicates an overload; the motor is overloaded or the torque output is too low, preventing the frequency from increasing. Additionally, it could be a problem with the motor parameters, so check if the motor parameters are accurately set."