How to maintain and upkeep frequency converters

A frequency converter is a power control device that uses frequency conversion technology and microelectronics technology to control AC motors by changing the frequency of the motor's operating power supply. The frequency converter mainly consists of rectification (AC to DC), filtering, inversion (DC to AC), braking unit, driving unit, detection unit, microprocessing unit, etc. The frequency converter adjusts the voltage and frequency of the output power supply by disconnecting the internal IGBT, providing the required power supply voltage according to the actual needs of the motor, thereby achieving energy conservation and speed regulation. In addition, the frequency converter also has many protection functions, such as overcurrent, overvoltage, overload protection, and so on. With the continuous improvement of industrial automation, frequency converters have also been widely used.

Daily maintenance of frequency converters:
The operator must be familiar with the basic working principle and functional characteristics of the frequency converter, and have common knowledge of electrician operation. Before daily maintenance of the frequency converter, it is necessary to ensure that the main power supply of the equipment is completely cut off; And wait for 3-30 minutes after the display of * on the frequency converter disappears (based on the power of the frequency converter) before proceeding. Attention should be paid to checking the voltage of the power grid, improving the surrounding environment of the frequency converter, motor, and circuit, regularly removing dust inside the frequency converter, and minimizing the failure rate of the frequency converter by strengthening equipment management.

(1) Cooling fan
The power module of the frequency converter is the most severely heated component, and the heat generated by its continuous operation must be discharged in a timely manner. Generally, the lifespan of a fan is about 20kh-40kh. According to the continuous operation of the frequency converter, the fan needs to be replaced every 3-5 years to avoid malfunctions caused by poor heat dissipation.

(2) Filter capacitor
Intermediate circuit filtering capacitor: also known as electrolytic capacitor, the function of this capacitor is to filter out voltage ripple after rectification, and also to decouple between rectification and inverter to eliminate mutual interference. It also provides necessary reactive power for the motor, which needs to withstand extremely large pulse currents and has a short service life. As it needs to store energy during operation, it must be powered on for a long time, The heat generated by its continuous operation, combined with the heat generated by the frequency converter itself, will accelerate the drying of its electrolyte, directly affecting its capacity. Under normal circumstances, the service life of a capacitor is 5 years. It is recommended to regularly check the capacitor capacity once a year. Generally, if the capacity is reduced by more than 20%, it should be replaced.

(3) The use of preservatives
Due to the production characteristics of some companies, the concentration of corrosive gases in various electrical MCC rooms is too high, resulting in many electrical equipment (including frequency converters) being damaged due to corrosion. To solve the above problems, a set of air conditioning system can be installed, using positive pressure fresh air to improve environmental conditions. To reduce the corrosion of components on circuit boards caused by corrosive gases, the frequency converter manufacturer can also be required to perform anti-corrosion processing on the circuit board, and spray anti-corrosion agents after maintenance, effectively reducing the failure rate of the frequency converter and improving its efficiency.

During maintenance, it is necessary to carefully inspect the frequency converter, regularly power on, and operate the motor at a low frequency of 2Hz for about 10 minutes to ensure the normal operation of the frequency converter.

Source: Internet