I. Safety Standard Inspection
1. Grounding Inspection: Use a grounding tester or multimeter to measure the grounding of the socket: A red light on the grounding tester indicates normal grounding.
Use a multimeter to measure the voltage between the live wire and the ground wire. It should be around 220V. If the voltage is abnormal, the grounding is poor.
The grounding resistance of the welding machine must be ≤4Ω, and it is forbidden to use steel bars or iron sheets to replace the ground wire.
2. Equipment Protection Inspection: Confirm that the welding machine casing is not deformed or rusted, and that the terminal protective covers are intact.
Check if the secondary wiring uses waterproof rubber-insulated copper core wire (length ≤30 meters). Welding cable with more than 3 joints needs to be replaced.
II. Key Component Testing
1. Insulation Resistance Testing: Use a megohmmeter (below 500V) to measure the insulation resistance between the input/output terminals and the casing. The normal value should be ≥2MΩ.
If the insulation resistance is <0.5MΩ, there is a risk of leakage.
2. Leakage Voltage Detection: Set the multimeter to AC voltage range (750V). Ground the black probe and touch the outer casing with the red probe.
Voltage > 36V indicates a dangerous leakage.
A slight voltage between the heating element and ground is normal.
3. Segmented Location Method: For complex equipment, measure in segments and compare with normal data to locate the leakage point.
III. Operational Precautions: Power must be disconnected before testing to avoid the risk of electric shock.
Regularly check insulation performance (e.g., monthly). If leakage is found, immediately stop use and repair.
