The Design of Low-voltage Welding Power Distribution

This paper is an effort to state clearly and to present a solution for the problems encountered in the design of one of the vital constituents of a-c restance-welder power supply¿the low-voltage feeder. The scope of the paper is much wider, however, since the determination of design loads from the probability standpoint for the purpose of determining maximum allowable impedance and expected temperature rise is a problem encountered in the design of all equipment common to a number of resistance-welding installations. The topics considered in the paper are: 1. Definition of voltage regulation as it applies to resistance-welding equipment. 2. Establishment of a criterion of good voltage regulation as defined. 3. Application of the theory of probability to the determination of maximum tolerable impedance and minimum copper section consistent with safe operating temperature. 4. Calculation of reactance of the closely spaced rectangular bar bus-type feeder, which the authors believe is best suited for the job, and its nearest competitor for low reactance, the concentric tubular feeder. 5. Calculation of maximum current capacity in terms of allowable temperature rise in the afore-mentioned type of bus feeders. 6. Determination of force between conductors in flat bar bus under short-circuit conditions, 7. The complete design of a feeder starting with typical data.