A frequency converter is a power control device that uses frequency conversion technology and microelectronics to control an AC motor by changing the frequency of its power supply. A frequency converter mainly consists of a rectification unit (AC to DC), a filter, an inverter (DC to AC), a braking unit, a drive unit, a detection unit, and a microprocessor unit. The frequency converter adjusts the voltage and frequency of the output power supply by switching its internal IGBTs, providing the required power voltage according to the actual needs of the motor, thereby achieving energy saving and speed regulation.
Because factory frequency inverters are used at high frequencies for extended periods, they require regular inspection, maintenance, and upkeep. Below, we will briefly discuss the inspection content and maintenance methods:
Daily inspection of frequency converters
Listening, visual inspection, touch, and smell, etc. General inspection content includes:
(1) Whether the surrounding environment, temperature and humidity meet the requirements.
(2) Check whether there is dust accumulation at the air inlet and outlet of the inverter, and whether it is blocked by dust accumulation.
(3) Whether the noise, vibration and odor of the frequency converter are within the normal range.
(4) Check whether the inverter's operating parameters and panel display are normal.
Maintenance and upkeep of low-voltage miniature frequency converters
Low-voltage miniature frequency converters refer to small-power frequency converters that operate on a low-voltage power grid of 380V (220V). They are mostly installed vertically in control cabinets, and their regular maintenance and upkeep mainly include:
(1) Regularly inspect dust removal
(2) Regularly check the main parameters of the circuit, such as whether the voltage of the main circuit and the control circuit is normal.
(3) Regularly check the external circuits and facilities of the frequency converter, such as checking whether the braking resistor and contactor are normal and whether the wire connections are loose.
(4) Determine the lifespan of components based on maintenance information, such as electrolytic capacitors and fans. Replace them promptly when the usage time exceeds the lifespan.
Regular maintenance and upkeep of high-voltage cabinet frequency converters
High-voltage frequency converters refer to frequency converters with an operating voltage of 6kV or higher. They are generally cabinet-type, and their periodic maintenance and upkeep, in addition to referring to the maintenance and upkeep clauses for low-voltage frequency converters, also include the following:
(1) Regular maintenance of busbars: Check for deformation, loosening and insulation damage.
(2) Regularly inspect the rectifier and inverter sections of the main circuit, such as using a multimeter to regularly measure the power semiconductor devices.
(3) Inspect the terminal blocks, such as whether the terminal blocks are aged or loose, and whether the wire insulation is damaged.
(4) If conditions permit, the filtered DC waveform, inverter output waveform and input power harmonic components can be measured.
