The present day automobile industries using large number of spot and arc welders, face serious problems in maintaining desired power factor in their fabrication shops. This is mainly due to single phase and highly unbalanced nature of load. It is every body's experience that at such places conventional contactor switching APFC systems do not work, but at the contrary deteriorate the situation further. Similarly, if the spot and arc welders are run on diesel generating sets, the utilization of the generating set is very poor, resulting in colossal waste of fuel. For such applications 'FAST RESPONSE THYRISTOR SWITCHED APFC SYSTEMS' are only the right solution.