Working principle of high-voltage inverter
1. High-voltage inverter is an electric energy control device that uses the on-off function of power semiconductor devices to convert industrial frequency power into another frequency;
2. The three-phase high-voltage electricity enters the high-voltage switch cabinet and supplies power to the power unit in the power cabinet after input voltage reduction and phase shifting;
3. The main control cabinet contains When the control unit passes through the optical fiber, it performs rectification, inverter control, detection and other processing on the power unit in the power cabinet, so that the frequency can be given through the operation interface as needed;
4. The control unit in the control cabinet will The control information is sent to the power unit for rectification, inversion and other adjustments to output the required level of voltage.
Daily maintenance of high-voltage inverters
General installation environment requirements for high-voltage inverters: minimum Ambient temperature -5℃, maximum ambient temperature 40℃. A large number of studies have shown that the failure rate of high-voltage frequency converters increases exponentially with temperature, and the service life decreases exponentially with temperature. If the ambient temperature increases by 10°C, the service life of high-voltage frequency converters will be halved. In addition, whether the high-voltage inverter is running well is also closely related to the cleanliness of the environment. Summer is a period when high-voltage inverter faults occur frequently. Only through good maintenance can the occurrence of equipment faults be reduced. Users must pay attention to this.
When maintaining high-voltage inverters in summer, attention should be paid to the temperature of the installation environment of the inverter, and dust inside the inverter should be cleaned regularly to ensure smooth cooling air paths. Strengthen inspections and improve the surrounding environment of inverters, motors and lines. Check whether it is tightened to ensure the correct and reliable connection of each electrical circuit to prevent unnecessary shutdown accidents.
1. Precautions for daily inspections
1. Carefully monitor and record the display parameters on the human-machine interface of the inverter. If any abnormalities are found, immediately Reflect;
2. Carefully monitor and record the ambient temperature of the frequency conversion room. The ambient temperature should be between -5℃~40℃. The temperature rise of the phase-shifting transformer cannot exceed 130℃;
3. When the temperature is high in summer, ventilation and heat dissipation of the inverter installation site should be strengthened. Make sure that the surrounding air does not contain excessive dust, acid, salt, corrosive and explosive gases;
4. Summer is the rainy season, so rainwater should be prevented from entering the inside of the inverter (for example, rainwater enters along the wind outlet) ;
5. Inverter cabinetThe filter on the door should usually be cleaned once a week; if the working environment is dusty, the cleaning interval should be shortened according to the actual situation;
6. During normal operation of the inverter, a piece of A4 paper of standard thickness It should be firmly adsorbed on the filter screen of the air inlet of the cabinet door;
7. The frequency conversion room must be kept clean and tidy and should be cleaned at any time according to the actual situation on site;
8. Ventilation of the frequency conversion room , lighting must be good, and ventilation and cooling equipment (air conditioners, ventilation fans, etc.) can operate normally.
2. Items that require maintenance after the inverter is shut down
1. Use a vacuum cleaner with a plastic nozzle to thoroughly clean the inside and outside of the inverter cabinet to ensure that the surrounding area of the equipment There is no excessive dust;
2. Check the ventilation and lighting equipment in the inverter room to ensure that the ventilation equipment can operate normally;
3. Check that the connections between the internal cables of the inverter should be correct. Reliable;
4. Check that all groundings in the inverter cabinet should be reliable and the grounding points are not rusty;
5. The inside of the inverter should be tightened again every six months (within) Each connecting nut of the cable;
6. When the frequency converter resumes operation after a long shutdown, the insulation of the frequency converter (including phase-shifting transformer and main circuit of the bypass cabinet) should be measured, and a 2500V megohmmeter should be used. The inverter can be started only after the insulation test is qualified;
7. Check the tightness of all electrical connections and check whether there are any abnormal discharge traces in each circuit, whether there is any strange smell, discoloration, cracks, damage, etc. ;
8. After each maintenance of the inverter, carefully check whether there are any missing screws and wires, etc. to prevent small metal objects from causing short circuit accidents in the inverter. Especially after making major changes to the electrical circuit, ensure that the electrical connection wires are connected correctly and reliably to prevent “reverse power transmission” accidents.
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