An inverter welder is a welding device that uses electronic technology to convert AC to DC and then to high-frequency AC via an inverter. It features a small size, is lightweight, has high efficiency, and has energy-saving and environmentally friendly characteristics, making it widely used for welding various metal materials. However, inverter welders can also encounter some faults during use, affecting normal welding operations. This article introduces some common faults of inverter welders and their repair methods, hoping to help you.
I. Causes of Inverter Welders Faults
Inverter welders can experience faults for various reasons, mainly including the following aspects:
Transportation Vibration: During transportation, the inverter welding machine may be subjected to severe vibrations or impacts, causing internal components to loosen or get damaged.
Operating Voltage Exceeding the Range: Inverter welding machines have a specific operating voltage range. If the input voltage is too high or too low, it can affect the welder's normal operation and even cause component damage.
Overload: Inverter welding machines have a rated load rate and maximum output current. Exceeding these parameters can lead to overheating or overcurrent, triggering the protection circuit or damaging components.
Improper Use: During use, the inverter welding machine should adhere to operating procedures, such as correctly connecting the welding power source, grounding wire, and output wire, and selecting appropriate welding parameters and electrodes. Improper operation can lead to malfunction or damage.
Harsh Operating Environment: The operating environment for the inverter welding machine should avoid high temperatures, humidity, dust, and corrosive gases, which can affect the performance and lifespan of the inverter welder.
Poor Quality of Some Components: Inverter welding machines are composed of many components, some of which may have quality issues or aging problems, leading to inverter welder faults.
II. Common Repair Methods for Inverter Welders
There are many repair methods for inverter welders, mainly including:
Resistance Method: Using a multimeter to measure the resistance value of each device in the circuit. Check whether the circuit is short or open. Such as whether the resistance has variable value damage, capacitance loss, transistor breakdown damage short circuit, or open circuit. This method is the simplest and most commonly used and is suitable for the preliminary fault judgment of resistors, capacitors, inductors, transistors, integrated circuits, etc.
Voltage Method: Measuring the working voltage of various points in the circuit when powered on to see if they are normal. This method requires familiarity with the circuit but provides accurate results.
Replacement Method: Replace uncertain components in the circuit with good ones to judge and eliminate faults. This method is generally used for machines where the fault location can be roughly determined and usually follows the resistance method.
Waveform Judgment Method: Using an oscilloscope or similar instruments to observe the working waveforms at various points and analyze the fault location based on the waveforms. This is the most direct method for analyzing complex faults.
III. Common Faults and Solutions of Inverter Welders
Common faults and handling methods for inverter welders include:
1. Startup Protection: When the inverter welder is turned on, the protection indicator light comes on with no output voltage. Causes of this fault include:
Field-effect Transistor (FET) Damage: The FET is a core component of the inverter welder. If it gets damaged, the inverter circuit cannot operate normally, triggering the overcurrent protection circuit. The inspection method is to measure the resistance of the FET using the resistance method to check for shorts or anomalies. The replacement method is to use an FET of the same model to replace the damaged one and check if the drive circuit is functioning correctly.
Secondary Rectifier Tube Damage: The secondary rectifier tube is the output section of the inverter welder. If it gets damaged, it will cause abnormal output voltage, triggering the overcurrent protection circuit. The inspection method is to measure the resistance of the secondary rectifier tube using the resistance method to check for shorts or anomalies. The replacement method is to use a secondary rectifier tube of the same model to replace the damaged one and check if the output circuit is functioning correctly.
Middle Board Transformer Damage: The middle board transformer is part of the drive section of the inverter welder. If it gets damaged, it will cause abnormal drive pulses, triggering the overcurrent protection circuit. The inspection method is to unplug the middle board transformer to see if the protection fault persists. If the fault disappears after unplugging, it can be roughly determined that the middle board transformer is damaged. The replacement method is to use a transformer of the same model to replace the damaged one and check if the drive circuit is functioning correctly.
Thermal Switch Damage: The thermal switch is part of the temperature monitoring system of the inverter welder. If it gets damaged, it will cause abnormal temperature signals, triggering the error protection circuit. The inspection method is to unplug the thermal switch from the control board to see if the protection fault persists. If the fault disappears after unplugging, it can be roughly determined that the thermal switch is faulty. The replacement method is to use a thermal switch of the same model to replace the damaged one and check if the temperature monitoring circuit is functioning correctly.
Control Board Protection Circuit Damage: The control board protection circuit is a major protection component of the inverter welder. If it gets damaged, it will cause abnormal protection signals, triggering the error protection circuit. The inspection method is to see if the protection fault persists after excluding other faults. If the fault remains, it can be roughly determined that the control board protection circuit is faulty. The replacement method is to use a control board of the same model to replace the damaged one and check if the main circuit is functioning correctly. If the fault persists after replacing the control board, other parts of the inverter welder might be faulty, and further inspection is needed.
2. Protection During Operation: If the protection indicator light comes on and the output voltage is cut off while the inverter welder is in operation, the possible causes include:
Welding Electrode Short Circuit or Poor Contact: The welding electrode is part of the output section of the inverter welder. If it shorts or has poor contact, it will cause excessive output current, triggering the overcurrent protection circuit. The inspection method is to measure the resistance between the welding electrode and the workpiece using a multimeter to check for shorts or anomalies. The solution is to replace or clean the welding electrode, adjust the welding parameters, and improve welding quality.
Large Input Voltage Fluctuations: The input voltage is part of the input section of the inverter welder. If it fluctuates significantly, it will affect normal operation, triggering the overvoltage protection circuit. The inspection method is to measure the input voltage with a multimeter to check for fluctuations or anomalies. The solution is to replace or adjust the input power source and use a stabilizer or filter.
High Ambient Temperature or Exceeding Rated Load: Ambient temperature and load rate are key factors affecting the temperature of the inverter welder. If the ambient temperature is too high or the load exceeds the rated level, it will cause welders to overheat, triggering the overheat protection circuit. The inspection method is to measure the internal temperature of the inverter welder using a thermometer to check for exceedances or anomalies. The solution is to lower the ambient temperature, reduce usage time, increase ventilation, or improve cooling.
3. No Output Voltage: If the inverter welder fails to produce normal output voltage after startup, the possible causes include:
Input Switch Damage or Not Turned On: The input switch is part of the input section of the inverter welder. If it is damaged or not turned on, the welder cannot operate normally. The inspection method is to measure the voltage across the input switch with a multimeter to check for continuity or anomalies. The solution is to replace or turn on the input switch and check if the input circuit is functioning correctly.
Auxiliary Power Components Damage: Auxiliary power components are part of the auxiliary section of the inverter welder. If they are damaged, the welder cannot operate normally. The inspection method is to measure the resistance, capacitance, and voltage regulation of the auxiliary power components with a multimeter to check for damage or anomalies. The solution is to replace the damaged auxiliary power components and check if the auxiliary power circuit is functioning correctly.
Drive Components Damage: Drive components are the drive part of the inverter welder. If they are damaged, the welder cannot operate normally. The inspection method is to measure the drive signal, drive current, and drive impedance of the drive components with a multimeter to check for damage or anomalies. The solution is to replace the damaged drive components and check if the drive circuit is functioning correctly.
Output Filter Components Damage: Output filter components are part of the output section of the inverter welder. If they are damaged, it will cause distortion or excessive noise in the output waveform, affecting welding quality and stability. The inspection method is to observe the output waveform with an oscilloscope to check for distortion or noise. The solution is to replace the damaged output filter components and check if the output circuit is functioning correctly.
4. Abnormal Output Voltage: If the inverter welder produces abnormal output voltage during operation, the possible causes include:
Abnormal Output Load: The output load is part of the output section of the inverter welder. If the load is abnormal, it will affect the output voltage. The inspection method is to measure the resistance, inductance, and capacitance of the output load with a multimeter to check for anomalies or mismatches. The solution is to replace or adjust the output load and check if the output circuit is functioning correctly.
Output Adjustment Components Damage: Output adjustment components are part of the control section of the inverter welder. If they are damaged, it will cause the output voltage to be improperly regulated. The inspection method is to measure the control signal, control current, and control impedance of the output adjustment components with a multimeter to check for damage or anomalies. The solution is to replace the damaged output adjustment components and check if the control circuit is functioning correctly.
In conclusion, while inverter welders are efficient, energy-saving, and environmentally friendly welding equipment, attention should be paid to their maintenance and upkeep to avoid faults. If faults occur, the causes should be promptly identified and appropriate measures taken to restore normal operation. For complex or severe faults, it is recommended to contact professional maintenance personnel for repairs. Thank you for your attention and support to the Megmeet Welding Technology website!
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