Hypertherm Powermax30 AIR Service Manual - Manual (Page 48)

48 Powermax30 AIR Service Manual 808850
4 – Operation
Understand duty-cycle limitations
The duty cycle is the percentage of time out of 10 minutes that a plasma arc can remain on when operating at an ambient
temperature of 40°C (104°F).
 35% duty cycle at 240 V / 30 A: With input power of 240 V and the output current set to 30 A, the arc can remain
on for 3.5 minutes out of 10 minutes without causing the unit to overheat.
 20% duty cycle at 120 V / 30 A*: With input power of 120 V and the output current set to 30 A, the arc can
remain on for 2.0 minutes out of 10 minutes without causing the unit to overheat.
* Although the duty cycle is rated for 30 A output, the recommended output current for 120 V circuits is 20 A or less. Operating the
system at 30 A on 120 V input can result in frequent tripped circuit breakers.
When you exceed the duty cycle and the system overheats, one of the following conditions occurs:
 The temperature LED illuminates, the arc shuts off, and the cooling fan continues to run. To resume cutting, wait for
the temperature LED to extinguish.
 The internal compressor LED and the temperature LED both illuminate. Allow the power supply to cool for 4 minutes
before using it again. If the problem persists, see
Internal compressor LED faults on page 66 for more
troubleshooting tips.
 When either condition occurs, leave the system on to allow the fan to cool the power
supply. The fan runs for 7 minutes after postflow.
Stretching the arc for prolonged periods while cutting can reduce the duty cycle. Stretching the arc requires the power
supply to generate a higher voltage output, which can cause it to run hotter and overheat more quickly.