Currently in development, Written-Pole® three-phase motors are energy efficient, unity power factor electric motors designed to meet the demanding needs of industry. These motors are intended for applications where energy efficient, unity power factor operation contributes to reduced operating costs and improved productivity.

Energy Efficient Operation

The energy efficient, synchronous design of Written-Pole® three-phase motors provides for superior operating efficiencies when compared to premium efficiency, three-phase induction motors, contributing to reduced operating costs and increased profits.

The energy efficient design of Written-Pole® three-phase motors ensures that these motors will exceed both current and future legislated energy efficiency requirements for three-phase electric motors in both Canada and the United States.

Unity Power Factor Operation

Since unity power factor input is achieved through synchronous operation, there is no additional contribution or amplification of system harmonics, as is the case with many capacitor or power electronics based power factor correction installations. Future designs call for the ability to select leading power factor operation, further compensating against high demand charges resulting from operation of other inductive loads on the distribution system.

Low Starting Current

The low starting current requirement for Written-Pole® three-phase motors further enhances their operation in applications where distribution considerations require reduced voltage starting of conventional induction motors. With a starting current of 2 to 2.5 times rated current, Written-Pole® three-phase motors eliminate the need for complex reduced voltage starting equipment. Their ability to start at rated voltage without compromising starting torque further enhances the capabilities of Written-Polẻ motors, contributing to improved operation of process equipment.

High Tolerance for Unbalanced Voltage

The application of Written-Pole ® technology allows these motors to exhibit a high tolerance for line voltage unbalances. Unlike conventional induction motors, which suffer a dramatic drop in efficiency and increase in operating temperature when operated on an unbalanced supply, Written-Pole® three-phase motors experience only a moderate decrease in efficiency and slight increase in operating temperature when operated on systems with up to 7.5% unbalance.

Flexible Synchronization

Written-Pole® technology allows for these motors to achieve electrical and magnetic synchronization prior to reaching the machine's rated speed. This capability allows for Written-Pole® three-phase motors to synchronize under load, a difficult task for conventional synchronous motors, making them ideally suited for many industrial applications.

Instantaneous Restarts

Conventional three-phase induction and synchronous motors can generate large torque transients when re-connected to a utility supply immediately after a momentary power interruption. For this reason, it is often necessary to delay the re-start of a motor until the motor slows to a speed which will limit the torque transient to an acceptable level, protecting both the motor and rotating equipment from damage.

The design of Written-Pole® motors allows them to overcome this limitation, lessening the impact of momentary power interruptions on facility operations. Written-Pole® technology enables the rotor poles to be reconfigured to match the utility supply immediately upon restoration of power eliminating the danger of large torque transients. As a result, the impact of momentary power interruptions, responsible for more than 95% of all utility interruptions, on industrial applications can be dramatically reduced.

This concept is used in unique class of electric motors referred to as Power-RideTM motors, which further enhance this capability by maintaining power to the driven load during momentary power

Written-Pole® is a registered trademark of Precise Power Corporation