10 learning methods for frequency converter maintenance! There is also a complete collection of various frequency converter passwords that must be collected!

There are many learning methods for frequency converter maintenance, but efforts are wasted if the direction is not right. Therefore, it is important to grasp the direction. In order to help everyone quickly grasp the knowledge of frequency converter maintenance, here are ten learning methods for frequency converter maintenance.

1. Alarm parameter inspection method
Example 1: A certain frequency converter has a malfunction and cannot operate, and the LED displays "UV" (abbreviation for under voltage). In the manual, the alarm is DC bus undervoltage. Because the control circuit power supply of this model of frequency converter is not taken from the DC bus, but from the AC input end through a transformer separately integrated control power supply. So it should be judged that the alarm is true. So, starting from the power supply, check that the input power voltage is correct and the filtering capacitor voltage is 0 volts. Due to the lack of action of the short-circuit contactor of the charging resistor, it is not related to the rectifier bridge. The fault range was reduced to the charging resistor. After the power outage, a multimeter was used to detect that the charging resistor was broken. Replace the resistor and it will be repaired immediately.
Example 2: After more than 3 years of use, a Sanken IF 11Kw frequency converter occasionally displays "AL5" (abbreviation for alarm 5) when powered on, and the instruction manual states that the CPU has been disturbed. After multiple observations, it was found that it occurred during the action of the charging resistor short circuit contactor. It is suspected that the interference was caused by the contactor. After adding resistance capacitance filtering to the control pin, the fault did not occur again.
Example 3: A Fuji E9 series 3.7 kW frequency converter suddenly experienced an OC3 (constant speed overcurrent) alarm shutdown during on-site operation. After power outage, it was re powered on and operated, resulting in an OC1 (acceleration overcurrent) alarm shutdown. I will first remove the wires from U, V, and W to the motor and use a multimeter to measure the infinite resistance between U, V, and W. During no-load operation, the frequency converter did not alarm and the output voltage was normal. It can be preliminarily concluded that there is no problem with the frequency converter. It turned out that there was a joint in the middle of the motor cable, which was covered in a wooden board in the distribution slot of the pit. The insulation tape was aged, and the factory was cleaned and water entered, causing an output short circuit.
Example 4: Sanken SVF303 displays "5", and "5" in the manual indicates DC overvoltage. The voltage value is sampled by the DC bus (about 530V DC) and then isolated by the optocoupler after voltage division. When the voltage exceeds a certain threshold, the optocoupler acts to give the processor a high level. Overvoltage alarm, we can check if the resistance changes and if there is a short circuit phenomenon in the optocoupler.
From the above examples, it is not difficult to see how important the alarm prompt of the frequency converter is in handling the problem, indicating the correct direction for handling the problem.

2. Analogy check method
This method can be an analogy of the same circuit itself, or it can be an analogy between a faulty board and a known good board. This can help the repairer quickly narrow down the inspection scope.
Example 1: The Sanken MF15 kW frequency converter was damaged and sent back for repair. The user cannot explain the specific situation. Firstly, use a multimeter to measure the input terminals R, S, and T. Except for a certain resistance value between R and T, the resistance between other terminals is infinite. The input terminals R, S, and T are respectively diode characteristics between the positive or negative poles of the rectifier bridge. Why are R and T different from the other two groups? Originally, there was a control power transformer inside the R and T circuit breakers, so there was a certain resistance value. From the above, it can be seen that there is no problem with the input part. Similarly, use a multimeter to check the resistance values between U, V, and W, and ensure three-phase balance. When checking the diode characteristics of the output relative to the positive and negative DC poles, it was found that the U phase IGBT was not working properly, indicating that there was a problem with the U phase IGBT. After removing it, it was confirmed that the IGBT was faulty. In the driving circuit, the three sets of characteristics of the upper bridge arm control circuit are consistent, while the three sets of characteristics of the lower bridge arm control circuit are consistent. By using a comparison method, it was found that Q1 was damaged. After replacement, the trigger pin resistance values are consistent in all groups, and power on to confirm that the PWM waveform is correct. Reassemble and power on for testing and repair.
Example 2: There is a frequency converter, and the phenomenon is that the panel display is normal, the digital setting frequency and operation are normal, but the terminal control is malfunctioning. Check with a multimeter that there is no 10V voltage on the terminals. Starting from the switch power supply, all groups of power supplies are normal, and it seems that the problem lies in the connecting wires. But finding 10V in 32 flat cables without drawings really takes some time. There happens to be a intact 22KW one, so first record the ground voltage of each pin of the 22KW flat cable, and then compare the ground voltage of each pin of the 37KW flat cable to quickly find the difference. The pins of the original slot were poorly soldered, but after a period of time, the oxidation of the frequency converter caused it to completely lose conductivity. It was repaired by re soldering.
Example 3: There is a carding machine equipment in a wool spinning factory that uses Siemens 440 frequency converters, with two 5.5KW and one 7.5KW operating synchronously. One of the 5.5KW units often experiences F0011 or A0511 shutdowns after two years of operation. Both of these alarms indicate motor overload. When the motor belt is disengaged and the motor and equipment are manually turned, there is no abnormal heaviness. Two 5.5KW motors were swapped and the original frequency converter alarm was found, indicating that there is a problem with the frequency converter. Analogy can not only be used to check the internal circuits of machines, but also to distinguish on-site problems.

3. Spare board replacement inspection method
Using spare circuit boards or circuit boards of the same model to confirm faults and narrow the inspection range is a very effective method. If there is a problem with the control board, there is often no other choice but to replace it, as most users rarely receive the schematic and layout diagrams, making it difficult to perform chip level maintenance. The circuit board other than the control board such as the power board and driver board can be repaired, which will be further introduced in other chapters. This mainly introduces the replacement of the control board.

4. Isolation inspection method
Some faults are often difficult to determine which area they occur in, and adopting isolation methods can simplify complex problems and quickly identify the cause of the fault.
Example: When repairing an Yingtai frequency converter, the phenomenon is that there is no display after power on, accompanied by a beep sound. Based on experience, it can be concluded that the switch power supply is overloaded, and feedback protection works to turn off the switch power supply output, and the beeping sound generated when it vibrates again and turns off again. Firstly, remove the control panel, and upon powering on, it was found that it remained the same. Then, disconnect the diodes of each group of power supplies one by one, and finally, it was found that there was a problem with the 15V used by the fan. But the fan does not have a running signal, it should not be a problem with the fan itself, it seems to be a problem with the front end of the fan. Finally, it was found that the characteristics of the 15V filter capacitor were incorrect. After removing the filter capacitor for measurement, it was indeed aging. Replace it with a new capacitor and it will be repaired.

5. Visual inspection method
It is to use people's hands, eyes, ears and nose to find the cause of the fault. This method is commonly used and used first. The maintenance principle of 'outside first, then inside' requires maintenance personnel to first use the methods of looking, smelling, asking, and touching when encountering faults, and conduct inspections one by one from the outside to the inside. Some faults can be quickly identified using this intuitive method, otherwise it will waste a lot of time and even have no way to start. Visual inspection can be used to check whether the connection of line elements is loose, whether the broken line contactor is burned, whether the pressure is frequent, whether the heating element is overheated and discolored, whether the Electrolytic capacitor is expanded and deformed, and whether the withstand voltage element has obvious breakdown points. After powering on, smell if there is a burnt smell and touch the heating element with your hand to see if it is hot. It is important to also ask the user about the process of the malfunction, which helps to analyze the cause of the problem and directly hits the key. Sometimes asking peers is also a shortcut.
Example: A Sanken IP 55KW frequency converter was damaged during the warranty period and there was no display when powered on. Open the machine cover and carefully observe each part. It is found that the charging resistor is burnt out, the contactor coil is burnt out, and the shell is burnt. After questioning, it turned out that the user's power supply voltage was low, and the frequency converter often stopped due to undervoltage. Therefore, a voltage booster was specially equipped for the frequency converter. However, the user did not notice that the voltage would return to normal at night, resulting in the first burning out of the contactor and then the charging resistor. The rectifier bridge and Electrolytic capacitor survived due to their relatively high withstand voltage. Replace damaged components and repair them.

6. Temperature rise and fall inspection method
This method is very effective for some special faults. Manually heating or cooling components with poor temperature characteristics to create "symptoms" or eliminate "symptoms" to identify the cause of the malfunction
Example: There is a malfunction in a Delixi frequency converter. The user reported that the frequency converter often stops due to parameter initialization, and the fault usually reappears within 20 to 30 minutes after resetting the parameters. Firstly, I believe that the fault should be related to temperature, as the temperature of the frequency converter will increase after running for this time. I used a hot air soldering table to heat the thermistor. When the temperature reached when the fan was started, I observed that the LED on the control panel suddenly lost power and then lit up again. Then it flickered intermittently. After removing the hot air for 30 seconds, the LED on the control panel no longer flickered, but displayed normally. Using isolation method, unplug all fan plugs, conduct another heating experiment, and eliminate the fault. Check that all fans are short circuited. It seems that after the temperature reached, the control board gave a fan operation signal, resulting in a short circuit of the fan causing the switch power supply to overload and turn off the output. The control board quickly lost power and caused parameter storage errors, resulting in parameter reset. Replace the fan and solve the problem.

7. Destructive inspection method
It is to take some means to cancel internal protection measures and simulate fault conditions to damage problematic devices. Highlight the faulty device or area. Firstly, it should be stated that this method requires great confidence in controlling the development of the situation, which means that the repairer should have a clear understanding of the state of the most severe damage, whether they can accept the most severe further damage, and have control measures to avoid more serious damage.
Example: During the repair of a frequency converter, when encountering a switch power supply fault, the protection circuit of the frequency converter acts, which can determine that there is a short circuit branch at the output end of the transformer, but the fault point cannot be measured statically. We use the destructive method to find static faultless devices. First, disconnect the feedback signal of the protection circuit to make it lose its protection function, then connect the DC power supply. It is required to use the Pressure regulator to slowly increase the DC voltage from 0v, and observe the relevant devices. If smoke is detected, immediately turn off the power supply and use a resistor to short-circuit the DC filter capacitor to quickly discharge. The smoke is coming from the rectifier diode of the fan power supply. Originally, the fan has been damaged due to short-circuit, and the control switch signal of the fan has been in the on state (device short circuit causing high level on state). As long as the switch power supply outputs normal voltage, the fan will short-circuit the fan power supply, causing switch power protection. However, during static measurement, the short-circuit state of the fan cannot be measured.

8. Tapping inspection method
The frequency converter is composed of various circuit boards and module connectors, with many solder joints on each circuit board. Any faulty soldering or poor contact will cause faults. Using an insulated rubber rod to tap on a suspected defective area, if the fault with the frequency converter disappears or reappears, it is likely that the problem lies there.
Example: The frequency converter of a certain factory has been running normally for more than 3 years, but suddenly stops without any signs, and there is no fault information displayed. After starting, it will rotate and stop intermittently. Upon careful observation, no abnormalities were found, and no issues were found during static measurements. After powering on, by tapping on the casing of the frequency converter, it was found that the operating signal would change with the tapping. After inspection, it was found that the screws at the FR terminal of the external terminal were loose, and the operating signal wire end was not crimped with a U-shaped terminal. It was directly connected to the terminal, and the wiring was pressed onto the wire skin, causing the screw to loosen due to vibration, resulting in a virtual connection between the control wire wire and the terminal. Crimp the U-shaped terminal and retighten the screw to troubleshoot the problem.

9. Brushing inspection method
Many special faults, occasional and subtle, make it difficult to diagnose and handle. At this point, the circuit board can be cleaned with water or alcohol, and at the same time, a soft bristle brush can be used to remove dust and rust on the circuit board, especially in areas with dense solder joints, vias, and circuits close to the 0 volt copper layer. Clean them thoroughly, and then dry them with hot air. Often achieving unexpected results. At least it helps with the application of observational methods.
Example 1: A certain frequency converter malfunction is not displayed. After preliminary testing, the rectifier and inverter parts are intact, so power on inspection is required. The DC bus voltage is normal, but the starting voltage of the switching power supply control chip 3844 is only 2v. The resistance value of the divider resistor is much smaller during online testing, but it is normal during offline testing. After using the washing method, the problem was resolved. Originally, the positive pin solder pad of a capacitor was very close to the 0V layer, and the residual flux left it in a semi conductive state.
Example 2: When the frequency converter is sent, there are several different alarm records. Various false alarms also appear during the power on test process. After carefully cleaning the solder joints of the flat cable socket connecting the control board and driver board, the problem was resolved.

10. Principle analysis inspection method
Principle analysis is the most fundamental method for troubleshooting. When other inspection methods are difficult to work, you can start from the basic principles of the circuit and conduct step-by-step inspections to ultimately identify the cause of the fault. When using this method, you must have a clear understanding of the circuit principle, master the logic level and characteristic parameters (such as voltage value and waveform) at each point at each time, and then use a multimeter and oscilloscope to measure and compare with the normal situation, analyze and judge the cause of the fault, narrow the fault range, until you find the fault.
Example: A frequency converter sent for repair simultaneously loses signals from the charging resistor short circuit relay, fan operation, and frequency converter status relay. After comparative experiments, it was confirmed that the problem lies in the control board. After analysis, the problem may be on the latch, as these signals are controlled by this chip. After replacement, it was indeed repaired.
Overall, the inspection of faulty frequency converters should be carried out from the outside to the inside, from the surface to the inside, from static to dynamic, and from the main circuit to the control circuit. The following three checks are generally mandatory.
Use a multimeter to test the diode characteristics and three-phase balance characteristics of the output terminals for the DC positive and negative poles, respectively. This step can preliminarily determine the quality of the inverter module, thereby determining whether it can output without load. If there is a phase to phase short circuit or unbalanced state, no-load output is not allowed.
Open the cover and observe. If no problems are found in the above two steps, you can open the casing, remove dust, and carefully observe the internal parts of the frequency converter for damage, burnt parts, and capacitor leakage.
The above are ten learning methods for frequency converter maintenance. Learning frequency converter maintenance through these methods can help you better get started, further master richer knowledge, and lay a solid foundation for proficiently learning frequency converter maintenance knowledge.

Here is a comprehensive collection of various frequency converter passwords for everyone:
01 Siemens brand
6SE70 book type frequency converter: When the password cannot be opened, simply change the data in P358 and P359 to the same.

02 ABB brand
ACS600 frequency converter: Enter the password "23032" in parameter 16.03, and set parameter 102.01 to false to enter and set all main control board parameters.

03 Mitsubishi brand
740 series frequency converters: When the password cannot be opened, simply unplug the panel and plug it in.

04 Emerson brand
TD3000: When the password cannot be opened, enter the password 8888.
TD3300: When the password cannot be opened, enter the password 20028.

05 Yaskawa brand
Yaskawa G5 frequency converter: The password is displayed in A1-04. Adjust to this parameter, and then press and hold the MENU and RESET keys simultaneously for 10 seconds to see the password. Adjust to A1-05 and enter the password to modify the parameters.
Yaskawa G7 frequency converter: When displaying A1-04, press RESET while pressing MENU to display the password settings for A1-05, and then input this password into A1-04.

06 Continental Brands
590 frequency converter: The universal password is 131122.

07 Schneider brand
Set the password, find COD in the SUP menu, and enter 6969.

08 Fuji brand
VG5 frequency converter: The password is the last parameter number 200, set to 0 and the data cannot be changed, and set to 1 and the data can be changed.
VG7 frequency converter: General password FFFF, which means you need to input FFFF to enter when powered on.

09 Hitachi brand
J300 frequency converter: To rename a multi-functional terminal to the "initialization" function (parameter C0-C7), then short circuit this terminal to the common terminal "CM1" (or P24), and then turn off the frequency converter before powering it on. If you want to change terminal "7" to the "initialization" function, set parameter C6 to "7".

10 Panasonic brands
Panasonic VFO frequency converter: Press MODE three times and press ▲ until 999 is displayed. Press ▲ and ▼ simultaneously and then press SET to reset the password.

11 LS brand
LG - iS5 frequency converter: Set FU2-94 to 240 to see the MAK parameters.

12 Delta brands
B-series frequency converter: The super password is 57522.
H-series frequency converter: The super password is 33582.
S1 series frequency converter: The super password is 575222.
A series frequency converter: Press the MODE and RESET keys together to display P256. Press the ENTER key to modify this parameter, changing 00 to 01. Press the ENTER key to exit and modify all parameters.

13 INVITEN brand
CHV, CHE, CHF series frequency converters: The super password is 50112.

14 Sanken Brands
Set the password and set the parameter CD900 to 36521.

15 Huichuan brand
The super password is 18181.

16 Dongyuan brand
M3 series frequency converter: Changing parameter P00 to 05 shows 65 parameters, changing P00 to 08 for 2-wire initialization, and changing P00 to 03 parameters is sufficient.

17 Ourui (formerly known as Huifeng) brand
The super password is: 1888.

18 Popular Brands
PI2000 frequency converter: (1) Set C01 to 222 and enter P14; (2) Set P14 to refresh the CPU with 3 pairs, and PI2000 will be displayed. Set C01 to 222 and enter P14 parameter setting. P14 will be set to 2, P01 will be set to model G and F, P02 will be set to inverter voltage of 380V, P03 will be set to inverter rated current, P04 will be set to voltage display, and P05 will be set to current display.

19 Xilin brand
The super password is 6860.

20 Jiaxin brand
TX-4T040C frequency converter: F00 refers to the user password setting, and the factory setting is 8888. If the password of the machine has been modified, the method to unlock the password is to power on the frequency converter and short circuit the JP4 solder joint to restore the factory password. JP4 is located above the motherboard CPU, with empty terminals and no connectors, only two pads. After short circuiting it, enter the parameter settings, confirm the factory password of 8888, and then modify the parameters after F00.