DUTY CYCLE. The duty cycle is defined as the time for which the current flows expressed as a percentage of the
complete cycle, which is taken as 5 minutes. Since the length of time for which the current flows during welding
operation varies from occasional to continuous, the duty cycle can vary from as little as 20% to maximum of 100%
on automatic operation. As conductor temperature varies according to the time in use as well as current, ratings
shown are given as a guide.
Automatic welding : Up to 100%
Semi - Automatic : 30 - 85%
Manual Welding : 30 - 60%
AMBIENT TEMPERATURES. Cable operating temperature also varies according to the prevailing ambient
temperature. EPR/CSP cables are designed to give optimum performance up to an operating temperature
of 85°C at an ambient temperature of 25°C. The reduction factors for increased ambient temperatures are.
Ambient temperature : 30°C 35°C 40°C 45°C 50°C 55°C
Reduction Factor : 0.96 0.91 0.87 0.82 0.76 0.79
OPERATIONS UNDER SEVERE CONDITIONS. High operating temperatures or prolonged maximum loading
of the cable reduces the life or makes the cable to hot to handle. Thus under conditions where a long service
life cannot be expected or where a high surface temperature is tolerable, the current rating for 25°C may be
applied up to an ambient temperature of 40°C.