One. The cause of the failure of the inverter welder
Since the inverter welder is an electronic product, its complicated structure and process, together with the instability of some components, can cause the welder to malfunction.
The common causes of failures are:
a. transport vibration
b. Working voltage exceeds the scope of use
c. overload
d. Improper use
e. The use environment is bad, such as high temperature and humidity
f. Poor quality of individual components.
two. Common maintenance method for inverter welding machine
1. Resistance method.
It is to measure the resistance value of each device in the circuit with a multimeter. Check if there is a short circuit in the circuit and open the circuit. If the resistance is damaged, the capacitor is out of capacitance, the transistor breakdown breaks the short circuit or the open circuit. This method is the simplest and most commonly used, and is suitable for initial fault judgment of resistors, capacitors, inductors, transistors, integrated circuits, etc.
2. Voltage method.
That is, when the circuit is powered, the working voltage of each working point of the measuring circuit is normal. This method requires familiarity with the circuit. However, the measurement results will be more accurate.
3. Replacement method.
That is, some components in the circuit that cannot be determined to be normal are replaced with good components to judge and eliminate the fault. This method is generally used on machines that can roughly determine the fault location, and is generally used as a follow-up method for the electrical resistance method.
4. Waveform judgment method.
Under certain conditions, the working waveform of each working point can be observed by means of an oscilloscope and the like, and the faulty part of the circuit can be analyzed from the waveform. This is the most intuitive method of fault analysis for analyzing some intractable diseases.
three. Common faults and treatment of inverter welding machine
1. The reasons for this failure caused by boot protection are as follows:
A. Field tube damage is overcurrent protection.
B. The secondary rectifier is damaged and is overcurrent protection.
C. The middle board transformer is damaged and is overcurrent protection.
D. The temperature control switch is damaged and is protected by mistake.
E. The control board protection circuit is damaged and is protected by mistake.
When the welder protection circuit is not working, when the welder over-current occurs, it will cause the bomber. Pay special attention to the protection circuit during maintenance.
Troubleshooting:
For the damage of the field tube and the secondary rectifier, the resistance of the field tube is generally measured by the resistance method, whether there is a short circuit or the field tube and the secondary rectifier resistance are abnormal. In judging whether the middle board transformer is damaged, it is generally necessary to remove the transformer plug to see if the welding machine still has a protection fault. If the medium board transformer is removed, there is no protection fault, and it can be roughly determined whether the medium board transformer is damaged, but The premise of judging this fault is that the secondary rectifier is not damaged and the welder output is not short-circuited. The metal processing WeChat content is good and worthy of attention. To judge the fault of the temperature control switch, just unplug the connection line of the temperature control switch on the control panel. If the fault disappears, it is the fault caused by the temperature control switch. In the case of protection circuit failure, in the case of other failures, the fault still does not disappear, and the protection lamp is still on, we can determine that the protection circuit has failed. To eliminate this fault, the resistance method is generally used to measure whether the components of the protection circuit are normal. In order to fix the fault.
2. No output reason analysis:
A. Power supply for the backplane (power strip), no 300 VDC output.
B. Auxiliary power supply is damaged.
C. There is no drive pulse.
D. Fault protection has occurred.
E. The internal connection of the welder has fallen off.
Troubleshooting:
The failure of the backplane (power board) is generally caused by damage to some devices, such as main relays, auxiliary relays, and thermistors. The inspection method generally uses an electric resistance method and a replacement method. If the auxiliary power supply is damaged, it is also possible to measure whether the components in the auxiliary power supply are damaged by the resistance method and the replacement method. It is possible to observe the working waveform of the auxiliary power source by using the waveform method to see if there is a hidden fault. After eliminating the above faults, it can be judged whether there is a fault without a drive pulse, which involves whether or not protection occurs. In some welders, there is also a gun switch circuit, and its abnormal operation also has no output pulse. The metal processing WeChat content is good and worthy of attention. For this problem, it is generally necessary to observe the driving pulse by means of an oscilloscope. In this fault we can also use the voltage method to check the power supply of each part of the welder to help troubleshoot.
3. No high frequency This fault is for argon arc welding and cutting machines.
Fault analysis: A. No high frequency caused by no output. B. No high frequency caused by damage to the high frequency circuit. C. No high frequency caused by disconnection or looseness of the cable.
Troubleshooting:
For no high frequency caused by no output, high frequency can be output by repairing no output fault. In the case of high-frequency circuit damage, the high-frequency circuit can generally be detected by the resistance method and the replacement method to detect damage to the device to repair the fault. If the fault is caused by the disconnection of the cable, check the cable and make sure that the cable is connected properly to correct the fault.
Add a few simple analytical solutions
1. Fault phenomenon: Bright voltage abnormality indicator Cause 1: Because the startup action is too slow, the switch contact is not synchronized.
Solution: You can turn it off and then on again.
Cause 2: The power supply voltage is out of phase or the input voltage is too high or too low (greater than 440V, or lower than 320V), which exceeds the normal working range of the welder.
Solution: Use a multimeter to measure the input voltage. Is the AC three-phase 380V normal?
2. Fault phenomenon: the fan does not turn, and the light voltage abnormal indicator light causes the cause: the power supply phase is missing. Solution: Using a multimeter to measure the input voltage, is the AC three-phase 380V normal?
3. Fault phenomenon: The fan does not turn, and the temperature abnormality indicator is on. Cause: The fan is damaged, causing the IGBT module to heat up.
Solution: Open the chassis and replace the fan.
4. Fault phenomenon: The temperature abnormality indicator is on. Cause: Exceeding the rated load rate, the IGBT temperature is beyond the normal use range and automatic alarm.
Solution: It can be turned on at no load, let the fan automatically dissipate heat, and the IGBT can resume normal operation after cooling.
To avoid excessive heating of the IGBT, please use the rated load factor indicated in the instruction manual.
5. Fault phenomenon: The current abnormality indicator is on. Cause one: If this phenomenon occurs with no load, or the welding current is not large, this phenomenon often occurs. Explain that the overcurrent alarm link is too sensitive.
Solution: Change the board.
Cause two: If the long-term working in the high current state, the current abnormality indicator light is on. Please immediately turn off the power in the standby room and then turn it on again. If it is not turned back on after the power is turned on, it means that the IGBT or main transformer in the welding machine has been damaged.
6. Fault phenomenon: The indication value of the no-load voltage on the voltmeter is low (less than 65V) after power-on.
Cause one: The display voltmeter pointer has a deviation.
Solution: Use the multimeter DC voltage file to measure (+), (-) the voltage between the two quick connector terminals, between 65V-75V. Indicates that the local no-load output is normal. Change the display voltage meter.
Cause two: AC contactor does not pull.
Solution: Find out the reason and replace the corresponding components.
Cause three: an IGBT is open.
Solution: Use the multimeter's downstream voltage file to measure (+), (-) the voltage between the two quick connector terminals, at 30V-45V. It is indicated that one of the IGBT tubes in the full-bridge inverter circuit has been opened, and the damaged module is detected and the new module is replaced.
7. Fault phenomenon: display voltage value is 0 when no load
Cause one: The voltmeter lead is broken or the display table is broken.
Solution: Use the multimeter's downstream voltage file to measure (+), (-) the voltage between the two quick connector terminals, between 65V-75V. Indicates that the local no-load output is normal. After shutting down, use the multimeter resistance file to measure the two leads of the voltmeter to (+), (-) the two quick connector ends are connected, indicating that the lead is not broken, it may be that the voltmeter is broken, change the table. The metal processing WeChat content is good and worthy of attention.
Cause two: circuit and board components are damaged.
Solution: Detect damaged boards and change boards.
Cause three: The IGBT is damaged.
Solution: Shut down and remove the IGBT tube to determine if the IGBT tube has been damaged. And change it.
8. Fault phenomenon; current is unstable or the welding effect is not good. Cause one: Some parts in the welder are in poor contact. (Example: The IGBT lead terminal is loose. The balance resistor at both ends of the electrolytic capacitor is off.)
Solution: Open the chassis, find the fault point, and reconnect.
Cause 2: The "thrust current" and "arc current" knobs on the panel are not adjusted properly.
Solution: In general, please adjust the "Thrust Current" and "Arc Current" knob to the minimum position.
Cause three: If the WSM type pulse argon arc welding machine is not stable in manual arc welding.
Solution: Please check the "DC" and "Pulse" switches on the front panel and point to "DC" during manual arcing. Otherwise, oscillations will occur.
9. General common welding machine (according to different operating methods of different welding machines) maintenance steps:
First, the IGBT explosion, the motherboard LM317 to the ground 2.7K resistance becomes larger, resulting in 22V voltage rise after the IGBT burst, replace the IGBT and change the 1 / 16W resistance is 1 / 8W, is a design defect, so repair 2 sets after 5 years of use Bad!
Second, sometimes there is no current regulation when the current does not work! Check the reversing electrodeless capacitor 380V0.56UF explosion, replace the normal, repair 3 sets 3, the welding machine no current or very small output other normal, check the panel remote control and machine control switch is bad, repair 4 sets four, no output check welder motherboard On the IR9630, IR630, 4 MOS is broken 2 replacement, repair 2 sets 5, the overheating fan is broken!
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