A three-phase welding machine is a device that uses a three-phase AC power supply to provide power for high-power welding equipment. There are two basic wiring methods for three-phase welding machines: the delta connection and the star connection. Below, I will briefly introduce the principles and steps of these two wiring methods.
Method 1: Delta Connection
The delta connection involves connecting the three input terminals of the 3-phase welding machine to the three fire wires of the three-phase power supply, as shown in the diagram below. The advantage of this connection method is that it can reduce the number of wires and transmission losses, making it suitable for high-power three-phase industrial loads. However, this method cannot provide single-phase voltage and cannot balance load current.
To use the delta connection, follow these steps:
Confirm whether the power supply voltage matches the rated voltage of the welding machine, typically 380V or 400V.
Ensure that the input terminals of the welding machine are marked, usually as L1, L2, L3, or A, B, C.
Check that the power cables are well insulated and grounded, generally red, yellow, and blue, or black, white, and gray.
Connect the input terminals of the welding machine to the power lines in no particular order, but ensure the connections are firm and reliable.
Connect the output terminals of the welding machine to the welding electrode holder and ground clamp, usually marked as + and -.
Turn on the power switch, adjust the output current of the welding machine, and start welding.
Method 2: Star Connection
The star connection involves connecting the three input terminals of the three-phase welding machine to the three fire wires of the 3-phase power supply and connecting a common point to the neutral line, as shown in the diagram below. The advantage of this connection method is that it can provide both single-phase and 3-phase voltage, and it can balance load current. However, this method requires four wires, and the common point must be grounded at the power supply.
To use the star connection, follow these steps:
Confirm whether the power supply voltage matches the rated voltage of the welding machine, typically 220V or 230V.
Ensure that the input terminals of the welding machine are clearly marked, usually as L1, L2, L3, and N, or A, B, C, and N.
Check that the power cables are well insulated and grounded, generally red, yellow, blue, and black, or black, white, gray, and green.
Connect the input terminals of the welding machine to the power lines in no particular order, but ensure the connections are firm and reliable.
Connect the common point (N) of the welding machine to the neutral line (black or green) and ground it protectively at the power supply.
Connect the output terminals of the welding machine to the welding electrode holder and ground clamp, usually marked as + and -.
Turn on the power switch, adjust the output current of the welding machine, and start welding.
Precautions for Operating a Three-Phase Welding Machine
In addition to the correct wiring methods, the following precautions should be observed to ensure the safe operation of a 3-phase welding machine:
Good ventilation: The three-phase welding machine generates a lot of heat and exhaust during operation, so ensure the working environment is well-ventilated to avoid overheating and gas accumulation.
Wear protective gear: The splashes and UV radiation generated during welding are harmful to the skin and eyes, so be sure to wear appropriate protective masks, gloves, and goggles.
Regular maintenance: Regularly check the cables, wiring, and components of the welding machine. If there is any damage or wear, replace it promptly.
Follow operating procedures: Strictly follow the welding machine's operating manual and safety regulations, and do not operate it beyond its capacity to avoid safety hazards.
Avoid damp environments: The three-phase welding machine is an electrical device, so avoid operating it in damp environments to prevent electric shock and equipment damage.
Three-phase welding machines are important in modern welding processes, but correct wiring methods and safe operation are crucial. By understanding the correct wiring steps and operational precautions for a 3-phase power supply, we can ensure the safe operation of the welding machine and achieve efficient welding results. Based on years of industry experience in the R&D and manufacturing of 3-phase welding machines, Megmeet Welding Technology advises everyone to prioritize safety when using three-phase welding machines and follow the correct operating procedures to ensure your safety and that of others.
Related articles:
1. How to Convert 3-Phase Welder to Single-Phase
2. How Much Power is Consumed by a 3-Phase Welding Machine?
3. Three-phase Welding Machine VS. Single-phase Inverter Welding Machine
4. Inverter Welder Problems and How to Solve Them?
5. How to Weld Aluminum with Inverter-Based Power Supplies?
