What is Duty Cycle on a Welding Machine?

Hello #SobatWilson

There is something we often overlook when buying a welding machine, even though it is very important in determining the right machine for our needs. On every welding machine, there is a nameplate that contains information about the machine's specifications, including the duty cycle.

So, what is meant by duty cycle?

And how does the duty cycle affect the selection of welding cables?

Referring to the AS/NZS 1995:2003 standard which regulates welding cables, the duty cycle is the percentage of time a welding machine operates within a specific period and current. In this case, the duty cycle period for the use of welding cables is regulated for several durations, including 30 seconds, 5 minutes, and 10 minutes.

Also read: What is Welding Cable?

For example, if the nameplate on the welding machine shows 160A at 60% duty cycle over a 10-minute period, this means the welding machine will operate at 160 amperes for 6 minutes, and then rest for 4 minutes for cooling. If the welding machine is operated continuously for 10 minutes without a break, the machine will only be able to operate at 124 amperes. If it is forced to run for more than 10 minutes without a break, the risk is that the insulation layer on the welding cable will melt, potentially causing more severe damage to the welding machine in the future.

The higher the output amperage used, the faster the machine will overheat, and the shorter the duty cycle will be. Conversely, if a lower output amperage is used, the duty cycle will increase.

So, how do you determine the correct welding cable that matches the duty cycle specifications of the welding machine?

From the information on the nameplate above, at 100% duty cycle, it shows 124A, and at 60% duty cycle, it shows 160A. This means you need to select a cable based on these requirements. Just like other types of cables, welding cables also have a maximum current rating. The difference is that welding cables also have an additional duty cycle period, as explained earlier.

Also read: Get to Know the Different Types of Welding Joints

From the table above (source: AS/NZS 1995:2003), it is known that the suitable welding cable for a welding machine with the duty cycle and current specifications mentioned earlier is a 25 mm² welding cable, where the cable's capacity at a 60% duty cycle can carry up to 175A, and at a 100% duty cycle, it can carry 165A. This means that the capacity of the 25 mm² welding cable is greater than the requirement needed for the welding machine with the specifications above.

The higher the duty cycle listed on the welding machine's nameplate, the larger the size of the welding cable needed.

Also read: Stainless Welding Methods: TIG Vs MIG, Which Way is Best?

The diagram table above explains the capacity of a 25 mm² welding cable, where, when the welding machine operates for 6 minutes (60% duty cycle), the cable can carry a current of up to 175 amperes, while the welding machine requires only 160 amperes for the 60% duty cycle, or continuous operation for 6 minutes.

To achieve optimal performance when using cables with a welding machine, choose cables with pure copper conductors and the appropriate size according to the specifications. Choose welding cables from WILSON CABLES.

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