ABB frequency converters are widely used, and various malfunctions are inevitable during use. There are generally two methods for handling ABB frequency converter faults (similar to other frequency converter faults): fault code analysis method and main circuit analysis method.

1. Fault code analysis method

If the ABB frequency converter has a fault, there are corresponding fault codes on the operation panel. Generally, when dealing with frequency converter faults, it is necessary to find its fault code on the operation panel and conduct a deeper analysis based on the fault code. Based on my personal experience in frequency converter maintenance and some common fault codes, I will briefly discuss some common fault handling methods.

1.1 Fault code: BRAKEFLT

Reason for malfunction: Brake failure, brake opening timeout or brake not opening properly.

Solution: Open the cover of the brake on site, forcefully open the brake coils in the program, observe the limit opening status of the brake, and if the brake cannot be opened or the mechanism is stuck, replace the brake;

If the distance between the limit opening and the limit sensing piece is far, adjust the distance of the sensing piece and ensure its fastening (based on the author's years of equipment management experience, the failure rate of electronic induction proximity switches is much lower than that of mechanical switches, and most important limit switches in our department have been improved from mechanical switches before installation to electronic induction proximity switches);

If the brake opens out of time, two methods can be used: ① If the brake opens slightly slowly, extend the delay time for opening the brake; ② The brake opens very slowly, and a new brake hydraulic push rod must be replaced at this time.

1.2 Fault code: MFCOMMERR

Reason for malfunction: Invalid communication between the master and slave buses.

Solution: Check the fiber optic connections between the master and slave bus connections, as well as between the host CH: and the slave CH:. Check if the connection is tight. If it is loose, it needs to be reinserted and the connection confirmed to be reliable. In addition, it is necessary to check whether the fiber optic communication is normal and whether the fiber optic head is clean. If it does not meet the requirements, it must be cleaned with precision electronic instrument cleaning agents or replaced with high-quality fibers.

If all the above situations are normal and the fault cannot be eliminated, force the output coil of the inverter contactor to move for about 5 minutes in the program, and the fault can be eliminated.

1.3 Fault code: SHORTCIRCUIT

Reason for malfunction: External motor cable malfunction or hardware malfunction of the frequency converter itself.

Solution: Disconnect the output line of the frequency converter, use a megohmmeter to measure the insulation condition of the three phases to ground and the three-phase electrical group. If there is a problem with the motor or cable, replace the motor and cable; If the output is normal, check the main circuit of the frequency converter, mainly the IGBT Inverter block and rectifier bridge, etc. How to determine if IGBT>inverter block and rectifier bridge are normal? Here, I tested the above intact electrical components with a multimeter diode setting, and the test results are as follows:

① For IGBT, when measuring C with the black probe and £ with the red probe of the multimeter, the resistance value is around 0.34MQ, otherwise it is infinite. The other four cases are all infinitely large.

② For the inverter block, when the black probe of the multimeter is used to measure the positive pole and the red probe is used to measure the negative pole, the resistance value is around 0.67 M Ω, otherwise it is infinite. When the black probe of the multimeter is used to measure the grounding electrode and the red probe is used to measure the negative electrode, the resistance value is about 0.34M Ω, otherwise it is infinite; When measuring the positive pole with the black probe and the grounding pole with the red probe of a multimeter, the resistance value is around 0.34M Ω, and vice versa, it is infinite.

③ For the rectifier bridge, when the black probe of the multimeter measures 1 and the red probe measures 3, the resistance value is around 0.37MC, otherwise it is infinite. The other four cases are all infinitely large.

If the test results deviate too much from the above results, it is recommended to replace them. If considering reducing the impact of maintenance on production time, the author suggests that it is more advisable to directly replace the frequency converter, because replacing a frequency converter requires controllable time, about 2 hours, while repairing due to the occurrence of the SHORTCIR-CULT fault code takes much more than 2 hours, and the time is uncontrollable.

1.4 Fault code: Ambinettemp

Reason for malfunction: The working environment temperature of the frequency converter is too low.

Solution: Consider adding air conditioning to the electrical room and increasing the working environment temperature of the frequency converter; If you want to resume work quickly in emergency situations, you can use heating tools such as hair dryers to increase the ambient temperature.

Ink smudge segmentation line

2. Main Circuit Analysis Method

The main circuit analysis method starts from the main circuit of the frequency converter, analyzing the causes and solutions of faults. Based on experience, when encountering faults in the main circuit of ABB frequency converters, the following aspects can be taken into consideration.

2.1 Faults caused by filtering capacitors

Reason for malfunction: Unstable voltage in the power grid, high internal temperature, and poor component performance.

resolvent:

① Mainly due to unstable equipment and susceptibility to electromagnetic interference;

② Replace high-quality components and improve ventilation conditions.

2.2 Inverter overheating

Reason for malfunction: The fan does not rotate and the air duct is blocked.

resolvent:

① Check if the fan coil is damaged;

② Clean up the dust accumulation in the cold air duct. If it is stuck due to lack of oil, add light oil first and then add some solid lubricating grease;

③ When replacing a new cold air fan, it is important to note that some fans come with an automatic rotation signal, while others do not. Replace the fan with the original model.

2.3 Excessive output current

Reason for malfunction: Output current exceeds the set limit and trips.

resolvent:

① Check if the motor load is short circuited;

② Check if the motor brake is fully open;

③ Check whether the mechanical rotating device operates flexibly;

④ Determine whether there is temperature rise, odor, abnormal noise and other phenomena during the operation of asynchronous motors;

⑤ After determining the motor and winding coil faults, pay attention to the original model and parameters when replacing them.

2.4 Brake malfunction

Reason for malfunction: The brake does not operate properly, the limit signal does not work, and the brake is mechanically faulty. resolvent:

① Check if the power supply to the brake is normal;

② Check if the mechanical transmission of the brake is normal;

③ Check for brake coil malfunction;

④ Check the brake limit and return signal;

⑤ Check if the contactor is functioning properly;

⑥ The main electrical fault of the contactor is caused by poor contact of a certain contact or loose screws of the contact terminal. Repair and replacement of new components should be carried out. If the brake is damaged, it should be rewired and replaced. When replacing, pay attention to the original model and parameters.

2.5 Encoder malfunction

Reason for malfunction: The frequency converter detected an error in the data signal feedback from the encoder or a communication interruption.

resolvent:

① Check if the encoder is properly connected to the motor or equipment;

② Check if the encoder signal cable is intact;

③ Check the connection between the encoder and the control board;

④ Check if the encoder is disturbed by surrounding devices;

⑤ Correct the encoder position and eliminate other interferences.

2.6 Interference Fault

Reason for malfunction: Mainly caused by conducted interference and electromagnetic induction interference.

resolvent:

① Mainly check whether each grounding wire is in good condition;

② Check if all shielded wires are connected properly.

conclusion

The above are typical faults and their solutions that have occurred during the use of ABB frequency converters in recent years. In order to effectively reduce the failure rate of frequency converters, daily inspection and maintenance are essential. Regular dust removal, regular inspection of bolts for looseness, checking for normal operation of cooling fans, checking for loose, overheated, or deformed cables and signal lines, checking for dry heat dissipation silicone on rectifier and inverter modules, and checking for abnormalities in control system wiring and various electronic components are the main focus of inspection and maintenance.

Common faults and maintenance strategies of ABB frequency converters

1、 Yao Bai

ABB, It is a well-known brand in Europe and even the world, with mature products such as high and low voltage frequency converters, high and low voltage electrical appliances, transformers, motors, power generation equipment, etc. It is widely used in various industries such as power plants, chemicals, papermaking, metallurgy, etc. It can be said that ABB's products have gained unanimous recognition from a large number of users in China.

ABB frequency converters occupy an important position in the frequency converter market due to their stable performance, rich optional expansion functions, flexible programming environment, good torque characteristics, and multiple series that can be used in different occasions. The market performance of ABB frequency converters in China is evident to all. ABB frequency converters rank among the top in the Chinese frequency converter market due to their strong brand effect and high social awareness.

2、 Market situation

ABB frequency converters have not been in the Chinese market for too long and have gone through a process of being unfamiliar, recognized, and accepted by a large number of customers, but their development has been very rapid. In the early days, the ABB frequency converters we could see mainly included low-power ACS300 frequency converters and standard ACS500 frequency converters. It should be said that these two series of frequency converters did not win many customers in China, and the ABB frequency converter that was truly recognized and accepted by the majority of users was the high-end frequency converter ACS600 using DTC control.

Stability, reliability, rich functionality, and flexible application are the magic weapons for ABB frequency converters to win the market. With continuous product updates, ABB has now launched an alternative product to the ACS600 frequency converter, ACS800, Compared with ACS600, in addition to maintaining the DTC control mode and all existing functions, the most obvious functional change of ACS800 is the addition of a simple PLC function, which does not require specialized tools and programming languages. Users can customize programming up to 15 modules. And it can draw the program on the functional module template to store the program. In addition, we also know that the ACS600 and ACS800 frequency converters have a wide range of optional functions. In addition to common I/O expansion modules and Profibus Modbus modules for communication, ABB has developed multiple macro programs specifically for different industries, including master-slave macros used in papermaking machinery, swing frequency macros used in textile machinery, PFC macros, PID control macros, torque control macros used in constant pressure water supply, and so on. It can be said that ABB frequency converters have a wide range of optional functions, basically meeting the needs of various industries for frequency converter functions. For different levels of customer groups, ABB has launched the ACS550 frequency converter with magnetic flux vector control, which is a frequency converter developed for mid-range customers and has a high competitive advantage in terms of cost-effectiveness. In addition, there are ACS400 frequency converters for low-end users, as well as economical ACSlOO and

ACS140 low-power frequency converter.

3、 Common faults and maintenance strategies

Due to the large sales volume of ABB frequency converters in the Chinese market, including some early used ACS2OO, ACS3OO, ACS50O, which have entered a period of frequent failures, many problems will inevitably be encountered during use. Below, we will discuss some common faults of ABB frequency converters with users:

For ACS300O frequency converters, a common fault we encounter is damage to the switching power supply. The ACS300O frequency converter switching power supply uses a waveform generator integrated block called EF1244, which has a similar function to UC3844. Due to sudden changes in operating voltage and damage to the load carried by the switching power supply, damage to this integrated block often occurs. As the electrolytic capacitor has reached its service life after a long period of use, the capacitor used for filtering has become the direct cause of damage to the switching power supply. We often encounter damage to the rectifier bridge of ACS3OO frequency converters during maintenance. Perhaps from an economic perspective, we have chosen the most compact three-phase full bridge rectifier from an international rectifier company, which has a small volume and load current, and poor heat dissipation. Therefore, damage may occur after a period of use. The probability of ACS300O main control board failure is also quite high. Communication failures between the control board and the motherboard, as well as CPU failures on the motherboard, occur from time to time, and these types of failures are usually difficult to troubleshoot. ACS300O uses Mitsubishi's IPM module, which has a relatively low probability of failure. If the module is damaged, it can only be replaced, but before replacement, it is necessary to ensure that the drive circuit is completely normal.

For ACS500O frequency converters, a common fault is damage to the drive thick film, which not only includes the drive circuit, but also short-circuit detection, IGBT module detection, overcurrent detection, etc. Due to its good protection function, the high-power module of ACS500O is rarely damaged. If the driver thick film is damaged during maintenance and there are no accessories available, we can only repair the thick film. Due to the fact that thick film components are soldered onto ceramic plates, heat dissipation is quite fast. Special attention should be paid not to damage the components by heating the soldering iron on them for a long time. Due to the limitation of usage time, the cooling fan of ACS500O may also malfunction. The common phenomenon is that only a "buzzing" sound is heard after power on, but the fan does not rotate. As it is an axial fan, the fan coil and bearings are often normal. After inspection, it was found that the deflection capacitor had malfunctioned. After replacement, it was restored to normal.

For the ACS600 frequency converter, it can be said that its performance and quality are quite reliable. However, due to the influence of the surrounding environment, improper parameter settings, and improper operations, the frequency converter may be damaged. Of course, natural damage is also an unavoidable factor for every brand of frequency converter. Unlike previous ABB frequency converters, the ACS600 frequency converter adopts fiber optic communication, greatly improving the communication time between the CPU board and the I/O board. However, it may also cause faults such as "LINKORHWC" and "PPCCLINK", which are not absolute due to fiber optic damage. The "PPCCLINK" fault is a common fault in ACS600 frequency converters, which can be caused by damage to the CPU board and I/O board. The switch power supply is damaged, which can also be encountered in ACS600 frequency converters. The fault mainly occurs on the switch tube. Due to the short circuit of the switch tube, it often causes a power resistor used for current limiting to burn out. The output short circuit fault of "SHORTCIRCUIT" is the most common type of fault we encounter. ACS600 adopts intelligent modules, and load faults and some problems during use can cause module damage, which often leads to damage to the drive board. Due to the high cost of spare parts, the cost of repairing the frequency converter is relatively high, so higher requirements are put forward for maintenance personnel at the board level.

For the newly launched ACS550 and ACS800 frequency converters, as they have only entered the market for a short time and there are no obvious typical faults that can be discussed with everyone, we will not discuss them here.

4、 Conclusion

It should be said that ABB frequency converters still encounter various faults during use, especially when spare parts costs are high. How to carry out circuit board level maintenance requires higher requirements for maintenance personnel. We also hope that more people engaged in the frequency conversion and speed regulation industry can join this ranks in the future to better solve some problems for our customers.

Common fault maintenance and handling measures for ABB frequency converters

Interference of ABB frequency converter on microcomputer control board

The solution is as follows:

(1) Good grounding. The grounding wire of high current control systems such as electric motors needs to be reliably grounded through the grounding busbar, and the shielding ground of the microcomputer control board should be grounded separately as much as possible.

(2) Add EMl filters, common mode inductors, high-frequency magnetic rings, etc. to the input power supply of the microcomputer control board.

(3) Add an EMl filter to the machine input.

(4) Electrical shielding and isolation analog sensors detect input and analog control signals.

The anti-interference problem of the inverter itself

The solution is as follows:

(1) Add inductance and capacitance on the input side of the machine to form an LC filtering network.

(2) The power cord of the frequency converter is directly supplied from the transformer side.

(3) When conditions permit, a separate transformer can be used.

(4) When using external switch value control terminals for control, it is recommended to use shielded cables when the connection line is long.

3. Grid quality issues

The solution is as follows:

(1) It is recommended that users add reactive static compensation devices to high-frequency impact loads such as welders, electroplating power supplies, and electrolytic power supplies to improve the power factor and quality of the power grid.

(2) For workshops with ABB frequency converters, it is recommended to use centralized rectification and DC common bus power supply.

(3) Install passive LC filters on the input side of the machine to reduce input harmonics, improve power factor, reduce costs, have high reliability, and achieve good results.

(4) The source PFC device is installed at the input end of the machine, which has good performance but high cost.

The above are the solutions to the three major interference problems of ABB frequency converters, hoping to be helpful to everyone.

Common faults and maintenance precautions for ABB frequency converters:

1. Do not install ABB frequency converters on vibration devices, as this can easily loosen the main circuit connection screws and cause damage.

2. Wiring issue: Try connecting the air switch to the input terminal to prevent severe burnout in case of a short circuit. The 'N' terminal cannot be grounded. Try not to make the control line too long. Do not install high current or frequently operated contactors nearby.

3. Inverters that often require emergency parking should not rely on their own brakes, but should increase additional braking voltage or mechanical brakes.

4. If the motor frequently runs at low speeds below 15HZ, the motor should be equipped with a cooling fan!

5. Dust and moisture are its deadly killers. Try to install it in air-conditioned rooms or in electrical control boxes with dust filters, and regularly clean the dust on the circuit board and radiator; If the inverter has been stopped for a while, try blowing the circuit board with a hair dryer before powering it back on.

6. Some ABB inverter manufacturers' machine cooling fans are broken, and overheating protection only occurs when the machine is damaged. Therefore, when the fan makes noise, it should be replaced.

7. Lightning protection is also important. Although this situation rarely occurs, it can be severely damaged when struck by lightning. The machine with constant pressure water supply is easily struck by lightning due to its anti explosion tube extending all the way to the sky.

How to deal with ABB frequency converter failure

After decades of development, the quality of ABB frequency converters is still relatively stable and reliable. In the past, ABB frequency converters in China were prone to problems, but now the probability of failure is not high. However, after using any product for a period of time, problems are prone to occur. When a problem first occurs, the key is to determine whether it is a problem with the ABB inverter itself or the peripheral circuit.

If the ABB frequency converter itself malfunctions, a fault code is usually displayed. Usually, common alarms include overcurrent, overload, overvoltage, undervoltage, ground fault, and insufficient output. Finding problems based on these alarm contents is more targeted. The fault code display for each ABB frequency converter may vary, but the content is generally the same. It is usually necessary to query the manual fault table based on the code displayed on the panel and handle the meaning of the landing fault code.

You can turn off the power first, wait for the power of the capacitor to be almost exhausted, which is equivalent to the motherboard having no power, and then turn on the power. At this point, check for any fault codes. If there is no fault code, it is usually caused by poor contact or load changes. If there is, it usually proves that this is an internal issue with the ABB frequency converter. Of course, this is only about and cannot be said to be correct. The actual situation is complex and requires further diagnosis at specific locations.

If it is an internal problem of ABB frequency converter, such as overcurrent and grounding alarm, most of the time it is due to IGBT module failure. You only need to use a multimeter to measure the main circuit to determine if there is a short circuit. Of course, in most cases, the optocouplers and resistive capacitive devices on the driver board will be damaged. These repairs require some electronic knowledge. You can find some industrial control and maintenance companies to help.

If the output is not synchronized, it is usually three-phase imbalance. Similarly, disconnect the ABB frequency converter from the motor and check separately. Simply measure whether the resistance matches the multimeter to determine motor imbalance.

Long term use of ABB frequency converters, aging of capacitors, and insufficient capacity often result in undervoltage and other phenomena.

Overvoltage is usually caused by high grid voltage, short acceleration and deceleration time, or heavy load.

If there is a misalignment such as err and it cannot be reset after power failure and power on, it is a motherboard fault and the motherboard needs to be replaced.

If it is not displayed, it is usually caused by a burnt out switch power supply or abnormal power supply.

After all, ABB inverters are connected to external things. In many cases, it may not necessarily be caused by itself. Search for the ABB frequency converter manual and on-site circuit electrical schematic according to the brand manual, and organize the overall start stop logic of the ABB frequency converter based on the drawings. For the situation where there is no alarm after the ABB frequency converter stops, this situation is very important.

1) Overcurrent fault: Reset the frequency converter If both 1 # and 2 # fail simultaneously, reset 2 # first, and then reset 1 #. If there is only one set of faults in 1 # or 2 #, simply reset it

Phenomenon: The command has been given (turned green), but the encoder remains unchanged and does not operate on site

Inspection: The frequency converter has no faults and the speed value is O

Solution: Ask the operator to stop the command. Then open the "Control Delay" variable monitoring table under blocks in the program. Enter 0 in the "modifyvalue" column after the corresponding timer, then click the "double arrow" icon on the toolbar or press F9o and have the operator restart.

2) PPOVerload (high temperature): When the temperature of the 1GBT node is too high, the current is limited. Temperature model activation. If the IGBT node temperature continues to rise during current limiting, a Ppover load alarm and fault will be generated.

3) EARTHFAULT (2330) (Programmable Fault Protection Function 30.17)

reason:

a. The load of the host system is unbalanced. It may be caused by motor failure or motor cable malfunction. Check that the overvoltage controller is in the on state (parameter 20.05).

b. The load imbalance of the main power supply may be caused by faults in the motor and motor cables, or internal faults. (Fault programmable, parameter 30.20) In the non parallel RlOl to R12I inverter, the trip current setting is too small. Check parameter 30.25

Method: Check the motor. Check the motor cable. Check that the motor cable does not contain power factor correction capacitors or surge absorbers.

4）SHORTCIRC（2340））

Reason: Motor cable or motor short circuit. Inverter output bridge fault.

Method: Check the motor and motor cables. Check for power factor correction capacitors or surge absorbers on the motor cables. Contact ABB representative.

5) MOTORPHASE (ff56) (Programmable Fault Protection Function 30.16)

Reason: Motor circuit malfunction. Motor phase loss. May be caused by motor failure, motor cable failure, thermal relay failure (if used), or internal malfunction. (Fault or alarm programmable, see parameter 30.19) Method: Check the motor or motor cable. If the motor is disconnected, this fault will be activated. Check the thermal relay (if used). 1 ⅛ SFaultFunction parameter, cancel this protection. If the cable and motor are in good condition, this fault will occur when the small motor (30KW) is running at low speed. In this situation, it is necessary to render this protection ineffective.

6）OVERCURRENT（2310）

Reason: Excessive output current. Exceeding the trip limit value. Check the motor load.

Method: If a trip occurs during tracking startup, check that parameter 21.01STARTFUNCTlon is set to AUTOo and all other modes remain unchanged. Check the acceleration time. Check the motor and motor cables (including phase sequence). Check if there are no power factor correction capacitors or surge absorption devices on the motor cable, and inspect the encoder cable (including phase sequence).

7）PPCCLINK（5210））

Reason: The fiber optic cable connected to the INT board has malfunctioned. Communication failure between RMlO and XINT boards or current measurement failure of XlNT board. If the intermediate DC circuit has been disconnected and the RMlO board is powered by an external power source, but the fault display is unnecessary, then this fault can be masked and only occurs when the motor is started. Parameter 30.24) (XlNT can be NINT, AINT,RNIT）o

Method: Check the fiber optic connection between the RMIO and NIT boards. Check the cable connections on the NPBU-XX board in the parallel inverter. If the fault persists, replace the NPBU board (referring only to parallel inverters) RNIo and NINT boards (in this order) until the fault disappears. Test with new fiber optic cables in the PPCC chain. Check the power section for any short circuits. This message may be caused by a functional module malfunction, short circuit, or overcurrent. Overloading of the auxiliary power supply can also cause communication failures in the PPeC chain.

8）RUNDISABLE

Reason: Failure to receive the operation permission signal resulted in an external interlock (DI2=0) circuit malfunction. There is a malfunction in the external device.

Method: Check the setting of parameter 16.01, enable the signal to start running, or check the relevant wiring. Check the circuit connected to the digital input DI2.

9) Underload (ff6a) (Programmable Fault Protection Function 30.13)

reason:

a. Underload detected. The motor load is too small, which may be caused by disconnecting the motor from the mechanical transmission equipment. (Fault alarm programmable, see parameter 30.16).

b. The motor load is too low. Possible caused by transmission mechanical failure.

method:

a. Check if the transmission equipment is faulty. Check the parameters of the UnderLoAD fault function.

b. Check the driven device. Check the FaUItFUnCtiOn (fault function) parameter.

10）CHOCOMMLOS

Reason: Communication interruption detected by CHO's receiving end, parameter 70.05 was used to select CONSENT

SPEEDl mode (can disable: see parameter 70.04)

Method: Check the fiber optic connection between the RMIo board and the upper computer system (fieldbus adapter). Test with new optical fiber. Check if the node addresses on the transmission system are correct. Check the status of the fieldbus adapter. Refer to the relevant fieldbus adapter manual. Once the FAB module and connection between the control system and adapter fail, please check the parameter settings of Group 51. Check if the communication or configuration of the bus host is normal.

11）CH2COMMLOS

Reason: Communication interruption detected by the receiver of CH2 (fault alarm programmable, see parameter 70.13)

Method: Check the fiber optic connection of CH2 between RMlo boards and verify if the fiber optic loop is closed. Test with new optical fiber. Check that there is a main drive in the MIF chain and the rest are slaves. Refer to parameter (70.08CH2M ∣ FMODABBPLC)

ABB frequency converter maintenance and regular troubleshooting methods

The maintenance and regular troubleshooting methods for ABB frequency converters are as follows:

1、 Operators must have basic knowledge of electrical operations and be familiar with the basic working principles and functions of frequency converters. Before inspecting and maintaining the frequency converter, wait for the frequency converter to discharge after the power supply of the equipment is completely cut off.

2、 Before routine inspection of the power supply to the frequency converter, check the temperature and humidity environment. When the temperature is too high, the frequency converter may overheat, and in terrible cases, the power supply of the frequency converter may be short circuited and disconnected. In the operation of a frequency converter, it is important to note that the cooling system is functioning properly during direct short circuits, such as whether the ducts are producing smooth or abnormal noise from the fan.

Whether the heat dissipation effect of the inverter directly affects its normal operation, whether the exhaust system of the inverter, such as the fan, is stable, and whether the air inlet is dusty or blocked are areas that you cannot achieve. In addition, it is necessary to check daily whether the motor has an overheated odor or produces abnormal noise to the frequency converter and motor, whether the current display on the frequency converter panel is too large, whether the current change amplitude is too large, and whether the current output of the UVW three-phase voltage is unbalanced.

3、 Regularly maintain and clean the air filter to cool the air ducts and internal dust. Check whether the screws, bolts, and plugs are loose, and whether the phase to phase resistance is short circuited, usually exceeding several tens of ohms.

If necessary, wipe the conductor and insulator with alcohol in a timely manner to see if it is corroded. If conditions permit, the measured voltage output by the oscilloscope's switching power supply and the smoothness distortion of the waveform measured by each rectangular wave driving circuit. Whether the ignition mark of the UVW phase waveform contactor contact is a sine wave, it is necessary to replace it with a new product of the same model or original capacity; Verify the effectiveness of the execution sequence of the control voltage protection operation test; Confirm no abnormalities and display circuit protection. It is recommended to regularly check the balance of output voltage, which should be done once a year.

4、 Although a frequency converter is composed of multiple components, its performance may gradually decline due to long-term use, which is the main reason for frequency converter maintenance failures.

The power module of the cooling fan inverter is the device that generates the most heat. The heat generated by continuous operation must be dissipated during this period, and the lifespan of the fan is usually 10 to 40 kilohertz. According to the continuous operation of the frequency converter for 2-3 years, the fan should be replaced once.