DC Motor Big Size DC Motor Medium Size DC Motor Machine DC Motor Big DC Motor Features ... field resistance, otherwise higher than seven times.5. For frame size Z4-315, Z4-355, Z4-400 and Z4-450, compensating ... windings are provided. For frame size Z4-250 and Z4-280 the motors are feasible with ... speed, and include excitation lose, excluding that of separate ventilating fans.