Precautions for Operation and Maintenance of High Voltage VFD (Variable-frequency Drive)

VFD (Variable-frequency Drive) general installation environment requirements: minimum ambient temperature -5°C, maximum ambient temperature 40°C. A large number of studies have shown that the failure rate of VFD (Variable-frequency Drive) increases exponentially with the increase of temperature, and the service life decreases exponentially with the increase of temperature. Lifespan will be halved. In addition, whether the VFD (Variable-frequency Drive) works well has a lot to do with the cleanliness of the environment. Summer is a frequent period for VFD (Variable-frequency Drive) failures. Only through good maintenance work can the occurrence of equipment failures be reduced. Users must pay attention.

During the maintenance of the high-voltage VFD (Variable-frequency Drive) in summer, attention should be paid to the temperature of the VFD (Variable-frequency Drive) installation environment, and the dust inside the VFD (Variable-frequency Drive) should be cleaned regularly to ensure the smoothness of the cooling air passage. Strengthen inspections and improve the surrounding environment of VFD (Variable-frequency Drive), motors and lines. Check whether the wiring terminals are tight, ensure the correct and reliable connection of each electrical circuit, and prevent unnecessary downtime accidents.

1. Matters needing attention in daily inspection

1.1. Seriously monitor and record the display parameters on the VFD (Variable-frequency Drive) man-machine interface, and report any abnormalities immediately.

1.2. Carefully monitor and record the ambient temperature of the inverter room. The ambient temperature should be between -5°C and 40°C. The temperature rise of the phase-shifting transformer cannot exceed 130°C.

1.3. When the temperature is high in summer, the ventilation and heat dissipation of the VFD (Variable-frequency Drive) installation site should be strengthened. Make sure that the surrounding air does not contain excessive dust, acids, salts, corrosive and explosive gases.

1.4. Summer is a rainy season, and rainwater should be prevented from entering the VFD (Variable-frequency Drive) (for example, rainwater enters along the wind outlet).

1.5. The filter screen on the VFD (Variable-frequency Drive) cabinet door should be cleaned once a week; if the working environment is dusty, the cleaning interval should be shortened according to the actual situation.

1.6. During normal operation of the VFD (Variable-frequency Drive), a piece of A4 paper of standard thickness should be firmly adsorbed on the air inlet filter of the cabinet door.

1.7. The frequency conversion room must be kept clean and tidy, and should be cleaned at any time according to the actual situation on site.

1.8. The ventilation and lighting of the frequency conversion room must be good, and the ventilation and heat dissipation equipment (air conditioner, ventilation fan, etc.) can operate normally.

2. Items to be maintained after VFD (Variable-frequency Drive) shutdown

2.1. Use a vacuum cleaner with a plastic nozzle to thoroughly clean the inside and outside of the VFD (Variable-frequency Drive) cabinet to ensure that there is no excessive dust around the equipment.

2.2. Check the ventilation and lighting equipment of the frequency conversion room to ensure that the ventilation equipment can operate normally.

2.3. Check that the connection between the internal cables of the VFD (Variable-frequency Drive) should be correct and reliable.

2.4. Check that all grounds in the VFD (Variable-frequency Drive) cabinet are reliable, and the grounding points are free of rust.

2.5. The connecting nuts of the internal cables of the VFD (Variable-frequency Drive) should be retightened every six months (inside).

2.6. When the VFD (Variable-frequency Drive) resumes operation after a long shutdown, the insulation of the VFD (Variable-frequency Drive) (including the phase-shifting transformer and main circuit of the bypass cabinet) should be measured, and a 2500V megohmmeter should be used. The VFD (Variable-frequency Drive) can only be started after the insulation is qualified.

2.7. Check the tightness of all electrical connections, check whether there are abnormal discharge traces in each circuit, whether there are strange smells, discoloration, cracks, damage, etc.

2.8. After each maintenance of the VFD (Variable-frequency Drive), carefully check whether there are any missing screws and wires, etc., to prevent small metal objects from causing VFD (Variable-frequency Drive) short-circuit accidents. Especially after making major changes to the electrical circuit, ensure that the connection of the electrical connection line is correct and reliable to prevent the occurrence of "reverse power transmission" accidents.