Inverter Routine Maintenance Guidelines
With the development of factory automation technology, frequency converters are increasingly becoming important drive and control devices. Therefore, ensuring the reliable operation of frequency converters has become a crucial issue for equipment maintenance and reducing downtime due to failures. The key to ensuring the reliable and continuous operation of frequency converters lies in daily maintenance.
Routine maintenance can be divided into the following categories:
I. Operational Data Recording and Fault Recording: Daily recording of inverter and motor operating data is required, including inverter output frequency, output current, output voltage, internal DC voltage, radiator temperature, and other parameters. Compare these data with established records to facilitate early detection of potential faults. If the inverter trips due to a fault, be sure to record the fault code and the inverter's operating conditions at the time of tripping for detailed fault analysis.
II. Routine Inspection of Frequency Converters:
Every two weeks, check and record the three-phase output voltage of the inverter during operation, and pay attention to comparing their balance; check and record the three-phase output current of the inverter, and pay attention to comparing their balance; check and record the ambient temperature and radiator temperature; check for any abnormal vibrations or noises from the inverter, and whether the fan is operating normally.
III. Inverter Maintenance: Each inverter should undergo dust removal and maintenance once per quarter. Maintenance involves removing accumulated dust and dirt from the inside of the inverter and its air ducts, and wiping the inverter surface clean; the inverter surface should be kept clean and shiny. During maintenance, carefully inspect the inverter for any overheating or discolored areas, cracked cement resistors, bulging or leaking electrolytic capacitors, protruding explosion-proof holes, or any abnormalities on the PCB board, including any overheated or burnt areas. After maintenance, restore the inverter's parameters and wiring, power it on, and run the motor at a low frequency of 3Hz for approximately 1 minute to ensure the inverter is operating normally.
IV. Inverter Overhaul: Inverter overhaul items:
Device status identification | Replacement method | Inspection after replacement | |
fan | Fans are common spare parts for frequency converters. Fan failure can be categorized into electrical failure and bearing failure. Electrical failure will cause the fan to stop working, which can be detected during routine inspections and should be replaced immediately. Bearing failure will result in significantly increased noise and vibration during fan operation, requiring prompt replacement. Alternatively, fans can be replaced after a certain period of use (generally around 3 years), as recommended in the corresponding frequency converter's instruction manual. | Original fan spare parts are recommended, but sometimes they are hard to find or have long lead times. In such cases, alternatives can be considered. Alternatives must be identical to the original in appearance and dimensions, use the same power supply, and have similar power consumption, airflow, and quality. | After replacement, a test run should be conducted to observe the fan's airflow, operating noise, and vibration. Run the machine continuously for about half an hour, and then observe the overall temperature rise. If everything is normal, the replacement can be considered successful. |
Main filter capacitor | The main filter electrolytic capacitor is a common spare part of the frequency converter. If the capacitor leaks, swells, or the explosion-proof hole is broken, it should be replaced immediately. During routine inspections, pay attention to checking the capacitor's capacitance. When the capacitance is less than 15% of the nominal value, it should be replaced as soon as possible. Alternatively, according to the relevant frequency converter's instruction manual, it can be replaced uniformly after a certain number of years of use. The lifespan of the main circuit filter electrolytic capacitor is closely related to the ambient temperature of the frequency converter. If proper care is taken during normal use and the frequency converter is installed in a good environment, the lifespan of the electrolytic capacitor can be greatly extended. | It is recommended to use original spare capacitors. However, if original spare capacitors are difficult to obtain or have long lead times, alternatives may be considered. Alternatives must be installed in dimensions identical to the originals, with a length less than or equal to the original, a voltage rating and nominal operating temperature greater than or equal to the original, and a total capacitance similar to the original. | After replacement, a test run should be performed, running at full load for 2 hours. If the capacitor itself does not overheat, the replacement can be confirmed as successful. |
High power resistors | Observe the surface color of the high-power resistor. If it is a cement resistor, check whether there are cracks on the surface of the resistor. If the resistor shows obvious signs of aging (blackening of the color, severe cracking), it should be replaced. | It is recommended to use original resistor spare parts, but alternatives can also be used. The alternative must have a similar power rating and resistance value to the original resistor, and the mounting method and dimensions must also be identical. | After replacement, a test run should be performed, with power off and power on repeated 3 times. Note the time interval between power off and power on. Then run it under full load for half an hour. If everything is normal, the replacement can be confirmed as successful. |
Contactor or relay Electrical appliances | Contactors or relays generally have a lifespan limited by the number of cumulative operations; once this limit is reached, they must be replaced. During routine inspections, if poor contact is found, they should be replaced immediately. | Original spare parts are recommended, but alternatives can also be used. The contact capacity and coil of the alternative must be identical to the original, as must the mounting method and dimensions. The quality must also be comparable. | After replacement, a test run should be performed, causing the contactor to operate repeatedly several times, and then running under full load for half an hour. If everything is normal, the replacement can be confirmed as successful. |
Structural components | The inverter's plastic casing may be damaged; replacement may be necessary depending on the specific situation. Internal mounting screws should be replaced if they are stripped or rusted. | When replacing the outer casing, original parts must be used, while screws and other structural parts can be replaced with substitutes of the same specifications and quality. | After replacing the screws, make sure to tighten them thoroughly and perform a full-load test to ensure that they do not overheat due to excessive contact resistance. |
Operation display sheet Yuan | If the inverter's operation display unit has missing displays or malfunctioning buttons, it must be replaced. | Replace with original products or compatible upgraded alternatives. | After replacement, power on the device to check if the display and operation are completely normal. |
Printed Circuit Board | Printed circuit boards are generally not replaced, but if severe overheating and blackening are found during routine inspections, replacement can be considered. | Replacement parts must be original parts. | After replacement, a full-load test of about 1 hour must be performed. Only if it runs normally can the replacement be confirmed as successful. |
The specific overhaul items for frequency converters are mainly determined based on the service life of the frequency converter and the results of routine inspections.
Statement: Shanghai Jinxin Electric Co., Ltd. owns all rights to this technical document. Anyone who wishes to reproduce it must indicate the source.
