Application of active load balancer in spot welding machine loads

Two phase spot welding machines create large unbalance within three phase currents. This causes deterioration of quality of the voltage at point of common coupling (PCC). Moreover, the industrial customers which create such large current unbalance escape the financial penalization because the unbalance in power does not reflect anywhere in the readings of energy meter which reads active energy consumption in terms of `kWh´. However the load unbalance does get reflected in `kVAh´ consumption. This paper objectively shows how the `kVAh´ read by the energy meter reads 16% more than the actual `kVAh´ consumed by the load in case of severe load unbalance. Thus, as far as utilities are concerned, migrating to `kVAh´ based tariff for such loads, automatically accounts for recovering financial penalties of as high as 116% of the actual energy consumed. However from the industry view point the industrial consumer would want to avoid this penalty by deploying a mechanism by which the utility always sees a balance set of three phase currents. This paper presents discussion on application of three phase three wire voltage source inverter as an active load balancer to be connected in shunt with the welding machine loads.