Written-Pole/sup (R)/ motor eliminates water hammer on irrigation and municipal water systems

Flywheel energy is stored in the high inertia rotor of a special Written-Pole/sup (R)/ motor. This Power-Ride/sup (R)/ motor is made inside-out, with the outside rotor spinning around the wound stator that is inside. Using this motor to drive a water pump causes slow rates of acceleration and deceleration. This leads to slow changes in flow rates of the water being pumped. Water hammer is caused by rapid changes in flow in water pipes. The use of this motor reduces the probability of water hammer. Other advantages are also described including very low start current, reduced line flicker, high efficiency and unity power factor. The paper discusses water hammer, Written-Pole motor technology, and presents case histories.