I. Operational data records and fault records:
Every day, the operating data of the frequency converter and motor should be recorded, including parameters such as the frequency converter output frequency, output current, output voltage, internal DC voltage of the frequency converter, and heat sink temperature. These data should be compared with reasonable data to help detect potential faults as early as possible.
If the frequency converter trips due to a fault, be sure to record the fault code and the operating conditions of the frequency converter at the time of the trip in order to analyze the cause of the fault.
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 frequency converter should undergo dust removal and maintenance once per quarter. Maintenance involves removing accumulated dust and dirt from the inside of the frequency converter and its air ducts, and wiping the surface of the frequency converter clean; the surface of the frequency converter should be kept clean and shiny. During maintenance, carefully inspect the frequency converter for any overheating or discoloration, cracked cement resistors, expanded 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 frequency converter's parameters and wiring, power it on, and run the motor at a low frequency of 3Hz for approximately 1 minute to ensure the frequency converter is operating normally.
IV. Inverter Overhaul:
Inverter overhaul projects:
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.
1. Fan
Component Condition Assessment: Fans are common spare parts for frequency converters. Fan damage can be categorized into electrical damage and bearing damage. Electrical damage will cause the fan to stop working, which can be detected during routine inspections and should be addressed immediately. Bearing damage will result in significantly increased noise and vibration during fan operation, requiring prompt replacement. Alternatively, according to the relevant frequency converter's instruction manual, fans can be replaced after a certain period of use (generally around 3 years).
Replacement method: Original fan spare parts are recommended. However, original spare parts are sometimes hard to find or have long lead times. In such cases, alternatives can be considered. The alternative must be identical to the original in appearance and installation dimensions, power supply, power consumption, airflow, and quality.
Inspection after replacement: After replacement, a test run should be conducted to observe the fan airflow, operating noise and vibration. Run continuously for about half an hour, and then observe the temperature rise of the entire machine. If everything is normal, the replacement (or substitution) can be considered successful.
2. Main filter capacitor
Component Condition Assessment: The main filter electrolytic capacitor is a commonly used spare part in frequency converters. If the capacitor shows signs of leakage, swelling, or cracked explosion-proof holes, it should be replaced immediately. During routine inspections, pay attention to the capacitor's capacitance; if the capacitance is less than 15% of the nominal value, replace it as soon as possible. Alternatively, according to the frequency converter's instruction manual, replacement can be done 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. Proper use and a good installation environment can significantly extend the lifespan of the electrolytic capacitor.
Replacement method: It is recommended to use original spare capacitors. However, sometimes original spare capacitors are hard to find or have long lead times. In such cases, alternatives can be considered. The alternative must ensure that the installation dimensions are exactly the same as the original, the length is less than or equal to the original, the withstand voltage and nominal operating temperature are greater than or equal to the original, and the total capacitance is similar to the original.
Inspection after replacement: 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.
3. High-power resistors
Component condition assessment: Observe the surface color of high-power resistors. 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, severe cracking), it should be replaced.
Replacement method: It is recommended to use original spare resistors, but alternatives can also be used. The alternative resistor must have a similar power rating and resistance value to the original resistor, and its installation method and dimensions must also be identical.
Inspection after replacement: 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 at full load for half an hour. If everything is normal, the replacement can be confirmed as successful.
4. Contactor or relay
Device condition assessment: Contactors and 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, the device should be replaced immediately.
Replacement method: Original spare parts are recommended, but alternatives can also be used. The contact capacity and coil of the alternative must be the same as the original, the installation method and dimensions must be the same, and the quality must be equivalent.
Inspection after replacement: 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.
5. Structural components
Component condition assessment: The inverter's plastic casing may be damaged; replacement should be determined based on the specific situation. If the internal mounting screws of the inverter are stripped or rusted, they should be replaced.
Replacement method: When replacing the outer shell, original parts must be used. For structural parts such as screws, replacement products of the same specifications and quality can be used.
Inspection after replacement: After replacing the screws, make sure to tighten them and conduct a full-load test to ensure that they do not overheat due to excessive contact resistance.
6. Operation Display
Device condition assessment: If the inverter's operation display unit has missing displays or malfunctioning buttons, it must be replaced.
Replacement method: Replace with original products or compatible upgraded alternatives.
Inspection after replacement: After replacement, power on the device and check whether the display and operation are completely normal.
7. Circuit board
Component condition assessment: Printed circuit boards are generally not replaced, but if severe overheating and blackening are found during routine inspections, replacement can be considered.
Replacement method: The original parts must be used for replacement.
Inspection after replacement: A full-load test of about 1 hour should be performed after replacement. Only if it runs normally can the replacement be confirmed as successful.
