... , 1500, 1000, 750, 600, 500, 400, 300 and 200 r/min, totally nine grades. Decrease armature voltage to make speed regulating under ... armature speed range can be down to the lowest 20 r/min at constant torque and stable running. 4.Separate excitation ... on static thyrisier controlled supplies, or from d-c generator; F. Performances of motors all comply with State Standard GB755. Fundamental ...