Rated Duty Cycle; Thermal Protection - Panasonic YC-500WX Operating Instructions Manual

3.2 RATED DUTY CYCLE

The rated duty cycle of this welding machine is 60 %. This means that the machine can weld for a total of 6minutes
out of any 10 minutes at the rated current, and then must cool down during the remaining 4 minutes to prevent
overheating.
As shown on the right figure, the allowable duty cycle varies with the output current. A duty cycle on the curved line
can be calculated using the following formula.
Allowable Duty Cycle
• Observe the lowest allowable duty cycle of the welding system components (typically either the welding machine
or the torch).
• Exceeding allowable duty cycle will cause the unit to stop automatically (with error displayed) or burning.
• If the ambient temperature is higher than 40 °C, limit the duty cycle to a level lower than the result of the formula.
• Output current values for pulsed welding are the average of the base and peak current values.
Allowable Duty Cycle vs. Output Current (10 minutes cycles, 40 ° C ambient temperature)
Duty cycle (%)
For your reference:
Duty cycle:
The percentage ratio of loading time to full time. A cycle of the full time shall be 10 minutes.
Rated duty cycle:
means the rate of use when loading the rated output current intermittently at the rated input voltage of the rated
frequency. Regarding the engine-driven welding power unit, however, it means when driving it at the rated number
of revolution.

3.3 THERMAL PROTECTION

Welding power source is equipped with a thermal switch at the radiator fin of IGBT to monitor the temperature.
The thermal switch is turned on when the welding power source goes into an abnormal temperature rise condition
due to over duty cycle or over output current, and stops the output.
Rated Output Current

（
Actual Ouput Current
(%)
100
50
0
387 450500
100 200 300
Output current (A)

）
2
Rated Duty Cycle
100% (387A)
60%
2
(%)