Starting way of electric commutator motor and scheme of its realization

The processing of welds at welding tubes of oil and gas pipelines now is carried out with a polishing machine powered by 220 V, 50 Hz. But, under field conditions, a source of electrical energy is the welding outfit. There is a problem of conversion of constant voltage of a welding outfit into alternate with given parameters. It is known, that at actuation of an electric tool, there is an impact current, since the braked electric motor has small electric resistance. Such a launch is harmful to the engine, and under conditions where there is an input source of restricted power comparable to power of the electric motor, it is impossible. One solution to this problem is an increase of power of the converter, that results in application of more potent power keys and other circuit components, i.e. increase of weight and overall dimensions of the device. The second way is providing a smoothly varying launch of the engine of an electric tool. Though the response time of the engine is also augmented, it succeeds in avoiding the deficiencies of the previous version.