Subclass 1/20: Arrangements for starting electric motors or dynamo-electric converters (starting of synchronous motors with electronic commutators H02P 6/2, H02P 6/22; starting dynamo-electric motors rotating step by step H02P 8/04; vector control H02P 21/00) for starting dynamo-electric motors or dynamo-electric converters for starting an individual dc motor by progressive reduction of resistance in series with armature winding