Q1Electrical Machine Design

The size of a rotating machine (its D²L product, per the output equation) is affected by: the rated output (kVA/kW), since higher output for a given speed requires a proportionally larger D²L; the rotational speed, since D²L is inversely proportional to speed for a given output (higher-speed machines can be smaller for the same power); the specific magnetic loading (Bav) and specific electric loading (ac), since a higher permissible value of either allows a smaller machine for the same output, though both are constrained by core saturation/iron loss and permissible temperature rise/copper loss respectively; the cooling method and permissible temperature rise, since better cooling allows higher specific electric loading and hence a smaller machine; and the choice of materials, since higher-grade magnetic and insulating materials can permit higher loadings and more compact designs.