Applicable Systems
ESAB Welding Equipment
Symptoms
The welder power supply has overheated. The thermal switch opens and the machine displays an overtemperature alarm. The output stops until the unit cools.
Possible Causes
- Cooling fan blocked or failed, preventing airflow across the power semiconductors
- Excessive duty cycle: the operator exceeded the rated 60% duty cycle at full current
- Heat sink fins clogged with dust and welding spatter
- Power inverter IGBT module degraded, generating more heat than normal
Troubleshooting Steps
- Step 1: Check the cooling fan operation by listening for airflow and feeling the exhaust
Replace the fan if it does not run or runs slowly - Step 2: Allow the welder to cool with the fan running for 10-15 minutes
The thermal switch resets automatically below 60C - Step 3: Clean the heat sink fins with compressed air from the exhaust side
Wear eye protection; clear all dust and spatter buildup - Step 4: Review the duty cycle rating and reduce the welding current or rest time
A 60% duty cycle at 200A means 6 minutes welding per 10-minute cycle
How to Reset
Reset: The welder restarts automatically once the internal temperature drops below the reset threshold.
Common Replacement Parts
- Cooling fan: 120mm, 24V DC, ball bearing (Match to welder model)
- Air filter: Washable foam, removable (Clean monthly in dusty environments)
- Thermal switch: 75C auto-reset type (Verify reset temperature matches OEM spec)
Frequently Asked Questions
- Q: What is duty cycle?
The percentage of a 10-minute period the welder can output rated current. 60% at 200A means 6 minutes welding, 4 minutes cooling.
- Q: How do I prevent overheating?
Keep the fan and vents clean, respect the duty cycle, reduce current in hot environments, and do not obstruct airflow around the machine.
- Q: Can I weld continuously at low current?
Yes. At currents below 50% of rated, most welders have a 100% duty cycle. Check the duty cycle curve in the manual.
Source: OEM Operation Manual
Category: Welding