In order to ensure reliable and stable operation of high and low voltage complete equipment and reduce downtime, daily use and maintenance are very important. In particular, it can be put into use only after it has been shut down or stored for a period of time and needs maintenance and testing. If the equipment is stored for a long time, condensation may occur when the ambient temperature changes, and liquid water will be generated at circuit boards, power devices, radiators, etc. These liquid water mixed with dust will rust cable joints, terminals, screws, and other devices, damage the electrical insulation, or even directly form a path, causing converter failure. The following work shall be done to ensure the stable operation of the equipment:

1、 Visual inspection:

Before power on, check whether the appearance of the inverter is deformed and whether the cabinet door is deformed. Open the cabinet door to check whether there are any abnormal phenomena such as moisture, rust, corrosion, discharge, falling off, and foreign matters in the cabinet.

2、 Drying and dehumidification treatment:

The high and low pressure complete equipment shall be dried and dehumidified by means of ventilation and heating. The electric drying air heater (the power of the industrial air heater is greater than 3000W, and the hot air is required to swing) is used to blow and heat it, so as to raise the temperature in the equipment. As the temperature rises, the relative humidity decreases. The drying time shall be controlled according to the dampness degree of the inverter (pay attention to the damage of optical fiber and cable caused by high temperature during drying).

The fan on the top of the inverter cabinet can be used for ventilation and dehumidification when the frequency converter is not seriously affected with damp. Manually force the top fan of the cabinet to work, so that the external fresh air enters the inverter cabinet, the absolute humidity of the air inside and outside the inverter cabinet is consistent, and the moisture inside the inverter is brought out of the inverter. The ventilation time is more than 8 hours.

3、 Dust removal:

If the dust is not cleaned timely after the inverter is shut down for a period of time, the heat dissipation of the internal components of the inverter will be affected and the components will be damaged for a long time. Thoroughly clean the dust in the converter cabinet before resuming use. Use a vacuum cleaner to clean the dust in the cabinet and on the surface of the unit (it is not recommended to use a hair dryer to blow the dust of the frequency converter, but use a hair dryer to remove the dust from the inside and outside of the frequency converter cabinet).

If the equipment has been operating for more than 3 months or the site environment is bad, the power unit shall be drawn out, and each unit shall be taken to the outdoor to clean the dust of the unit with a hair dryer or compressed air. When removing the unit, pay attention to the optical fiber being hung or broken, and do not touch the board card and power components during soot blowing. After the dust is cleaned, fasten each plug on the unit board. Check the fastening of the screws on the power device. At the same time, use a multimeter to test whether the fuse is damaged. Clean the dust in the power cabinet when the unit is pulled out. For 5000 series models, the unit plug should be carefully wiped and cleaned with a cloth dipped in a small amount of alcohol, and it can only be used again after the inverter is dried.

After half a year of operation or the site environment is relatively harsh, the dust of the site transformer needs to be cleaned. Clean the dust before high voltage and low voltage of each winding with a blower. Check whether there is any foreign matter between the iron core and the coil, whether the connecting wire is broken or exposed, and whether the coil is discolored or blackened.

4、 Dust cleaning of filter screen:

The dust filter screen of the frequency converter will accumulate some dust during use or long-term storage. The filter screen must be cleaned before the frequency converter is used. After the dust filter screen is removed, it can be blown clean with a blower or compression control. The filter screen can be cleaned with water when the viscosity of dust on site is not large, and can be used after drying.

5、 Inspection of primary and secondary circuit cables:

Check the tightness of all cable connections, and check that each cable has no abnormal discharge trace, strange smell, discoloration, crack, damage, etc. Check whether the primary input and output high-voltage cables are correct and whether the wiring phase sequence is correct. Use a multimeter to ensure that the high-voltage power supply incoming line is not confused with the motor line. Check whether the wiring is tight and the contact surface under reasonable force is reasonable. After the frequency converter is maintained, the wiring of the primary cable must be checked to prevent "reverse power transmission".

Fasten all control terminals, adapter plugs and external terminals in the frequency conversion cabinet. Check whether the cabinet, PE and signal grounding are reliably grounded.

6、 Cable insulation inspection:

When the speed regulating device of the high and low voltage complete equipment recovers operation after a long shutdown, the insulation test shall be carried out for the high-voltage cable. Use a 2500V megger to measure the phase to ground and phase to phase insulation resistance respectively, and start the speed regulating device only after the insulation is qualified. When testing the insulation of output cable, the cable shall be removed for testing to prevent breakdown of power devices.

7、 Transformer inspection:

Fasten the lead terminals, pins, grounding screws and connecting bus screws. If they are loose, remove the screws or replace the spring washers and screws until they are in good contact. Use a 2500V megger to test the insulation of the primary side of the transformer.

8、 Inspection of control machine:

Check whether the installation of the control box is tight, whether the control board cards are firmly inserted, and whether each terminal on the board card is tight. Check whether the optical fiber plug of PWM board is fastened. Check whether the angle of the optical fiber is too large and whether the force is too large.

9、 Room preheating:

Before power on of high and low voltage complete equipment, the ambient temperature shall be above 0 ° C to prevent damage to internal components of frequency converter. According to the site environment, the frequency conversion room shall be heated or the air conditioner shall be set to the heating mode to make the temperature of the frequency conversion room reach above 0 ℃.

10、 Power unit capacitance activation:

If the frequency converter is stored for more than 3 months, the power module needs to be charged and discharged for 3 times, each time for 30 minutes. After the unit electricity is completely discharged, it needs to be charged once, and the capacitance in the module is activated by the capacitor re discharge.

11、 System preheating:

Do not run on behalf of the load immediately after the inspection is completed. Energize the high-voltage power to make the high-voltage and low-voltage complete equipment ready, and the frequency conversion enters the hot standby state. The hot standby time is longer than 2 hours. If the storage time is too long, the hot standby time should be extended. When the fan on the top of the cabinet rotates during the frequency conversion hot standby, the internal operation of the frequency conversion can be eliminated, and the capacitor module in the power unit can be activated.

12、 Cleaning of inverter room:

The operation frequency conversion room must be kept clean, and shall be cleaned at any time according to the actual situation on site to keep the ground clean. Ensure humidity and prevent water leakage. The site with large dust shall ensure indoor sealing. Ensure that the cable trench is dry and tidy.

After the speed regulating device of high and low voltage complete equipment is tested, carefully check whether there are missing screws and wires, etc., to prevent short circuit accidents of high voltage frequency conversion speed regulating device caused by small metal objects.