A machine has a duty cycle of 300 Amps at 20%. How long can you weld at 300 Amps continuously before the machine shuts down?

A machine has a duty cycle of 300 Amps at 20%. How long can you weld at 300 Amps continuously before the machine shuts down?

• A. 1 Minute
• B. 2 Minutes
• C. 3 Minutes
• D. 4 Minutes

Answer: (B)

Duty cycle is the fraction of time you can weld at a given current before the machine overheats, usually stated as the amount of on-time within a 10-minute period. So at 300 amps with a 20% duty cycle, you can weld for 20% of that 10-minute window. Compute 20% of 10 minutes: two minutes. That means you can weld at 300 amps for about 2 minutes before the machine needs to cool. After those 2 minutes, you should rest the welder for the remaining 8 minutes of the 10-minute cycle to stay within the rating. So the best answer is two minutes of continuous welding at 300 amps within each 10-minute cycle. The other durations correspond to higher duty cycles than 20%.

Duty cycle is the fraction of time you can weld at a given current before the machine overheats, usually stated as the amount of on-time within a 10-minute period. So at 300 amps with a 20% duty cycle, you can weld for 20% of that 10-minute window.

Compute 20% of 10 minutes: two minutes. That means you can weld at 300 amps for about 2 minutes before the machine needs to cool. After those 2 minutes, you should rest the welder for the remaining 8 minutes of the 10-minute cycle to stay within the rating.

So the best answer is two minutes of continuous welding at 300 amps within each 10-minute cycle. The other durations correspond to higher duty cycles than 20%.