Document ymZ7JDkXaEE4gYMGexzk94ejd

summer . POWERFAX 19 3 2 BUioU SOO-ka.-a., ISO- to 960-r.pjn. inserted motor-generator tel supplying power to 87 induction motors for run-out table on a continuous mill. The diretl-eurrtnl end of the unit is a compensated motor. PAPER PRESENTED BEFORE THE CONVENTION OF THE ASSOCIATION OF IRON AND STEEL ELEC TRICAL ENGINEERS IN PITTSBURGH, PA., JUNE 22, 1932 By M. E. THOMPSON, Consulting Engineer, and I. S. NIPPES, Electrical Engineer, Eniott Company, Ridgway, Pa. he past few years have type have often been .selected to Twitnessed an increasing use of direct-current motors and insure the necessary flexibility and refinements in speed adjustments generators in the steel industriny. connection with modern high Reversing and continuous mills are speed mills. The compensated gen producing a considerable variety erator and motor have been very of products with speeds and re important factors in these develop finements that were considered im ments. This fact, as indicating the possible a few years ago. This generaltrend, makes it worth while greater speed of production and to consider in some detail the char variety of refined products have acteristics and application of com made it desirable to employ elec pensated machines. tricdrives havingconsiderableflex The direct-current compensated ibility. At the same time, dose type of machine is wound with a voltage regulation in generators special winding in the pole faces. and dose speed regulation in'mo The method employed is to slot tors are needed. Direct - current the pole faces and to place a wind motors of the adjustable - speed ing about the commutating pole as a center, with a part of the wind ing distributed in the pole faces. The extra winding necessary to produce a commutating flux is con centrated on the commutating poles located midway between the main poles. This winding is con nected in series with the armature winding. In the construction of a machine, the compensating wind ing is placed as near to the arma ture winding as possible and ar ranged in such a manner that they carry load current in opposite di rections. The function of a compensating winding is twofold: First, to create a commutating field which will vary in exact pro portion to the armature current. This variation produces the cor rect condition for sparkless com mutation at all loads. Second, to prevent the magnetic field produced by the armature conductors when carrying current from distorting and croes-magnetizing on the main shunt field, which action has an important in fluence upon the performance char acteristics of a machine. '>:>[ ' i