Description; Introduction; Duty Cycle - ESAB Heliarc 252 Instruction Manual

SECTION 1

DESCRIPTION

1.1 INTRODUCTION

The Heliarc 252 and Heliarc 352 welding power sources are constant
ac/dc
current AC/DC welding power sources for high quality tig and stick welding in
both the AC and DC mode. The unique characteristics of the magnetic and
solid state circuits provide excellent arc conditions for all tig welding as well
as high alloy stick electrodes. The non-saturating current limiting reactor and
electronic feedback control prohibits high current surges inherent with saturable
reactors or solid state SCR control alone, therefore reducing spatter on stick
electrodes as well as tungsten spitting when tig welding. The electronic firing
circuit utilizes a voltage compensating circuit which compensates for line volt-
age variations of +/-10 percent.
Through its unique design, the Heliarc 252 and Heliarc 352 combines all
ac/dc
of the latest state-of-the art magnetic and solid state concepts to provide the
wide range volt-ampere curve characteristics needed for a constant current
AC/DC power source - see Figure 1-1 or 1-2. Refer to Table 1-1 for technical
specifications.

1.2 DUTY CYCLE

Duty cycle is defined as the ratio of load time to the total time. Standard current
ratings are based on a 10-minute cycle. This machine is rated at 40 percent
duty cycle which means the rated load is applied for a total of 4 minutes and
shut off for a total of 6 minutes in a 10-minute period. However, if the welding
current is decreased, the duty cycle can be increased. Conversely, if the weld-
ing current is increased, the duty cycle must be decreased. Figure 1-3 or
1-4 enables the operator to determine the safe output of the power source at
various duty cycles. Note that the duty cycle of the unit is approximately 50%
less when Balance Control is in the "max. penetration" position
11