Written Pole Technology

WRITTEN-POLE ELECTRIC MOTORS

Presented by:Nidhi Pansari (3rd elec)Preeti Baid (3rd elec)

2

CONTENTS

•LIMITATIONS OF CONVENTIONAL TECHNOLOGY•CONSTRUCTION•WRITTEN-POLE TECHNOLOGY•OPERATION•OPERATIONAL BENEFITS•ADVANTAGES•WEATHER CONDITIONS•APPLICATIONS•CONCLUSION

LIMITATIONS OF CONVENTIONAL TECHNOLOGY

1.Dependence of speed on no. of poles of rotor.

speed = 120 X frequency no. of poles2.The machine must have even no. of

poles and deviating from this condition will cause unstability at its rated speed.

AN INNOVATIVE PATENTED

TECHNOLOGY• In the 1990’s, with support

from the EPRI, the Precise Power Corporation of Bradenton, Florida, developed a new concept in electric motors called the Written Pole® electric motor.

WRITTEN-POLE TECHNOLOGY

• The patented Written-Pole® Technology allows the magnetic pole pattern on the magnet layer to be changed to a desired pattern while the machine is rotating and therefore breaks the relationship between rotor speed and output frequency.

Contd..

CONSTRUCTION

Contd…

• Written Pole motors use similar construction techniques found in conventional motors.

• A continuous layer of ferrite magnets on the surface of the rotor, along with a high-density exciter winding contained within the stator winding .

• The basic platform consists of a conventional steel shaft inserted into a lamination stack containing a high resistance rotor cage.

• The high resistance cage is a key factor in limiting the starting current of Written-Pole motors.

• The stator lamination stack is constructed using low loss electrical steel laminations.

• The concentrated excitation windings are contained within the stator structure and are located between the main stator windings.

OPERATION

• A written-pole motor employs one of three modes of operation based on the rotational speed of the machine:

1. START MODE 2. WRITTEN POLE MODE 3. RUN MODE.

OPERATIONAL BENEFITS

Feature Conventional

WP

Speed 3,560rpm 3600 rpm

Efficiency 85% 93%

Power factor 90.5% 100%

Full-load power 53kW 40kW

Full-load torque 73.7 ft-lb 73 ft-lb

Starting torque 88 ft-lb 82 ft-lb

Full-load current 219 amps 173 amps

Locked rotor current

1450 amps 312amps

Cost (p.u.) 1.0 1.2

ADVANTAGES

1. Low starting current requirements

2. Energy efficient operation3. Unity power factor operation4. Simple construction5. Low temperature rise6. High inertia starting7. Instantaneous restart capability8. Ride through characteristics9. Three-phase applications

WEATHER CONDITIONS

• The Written-Pole motor is designed to operate in ambient temperatures ranging from 32ºF to 104ºF.

• However,test results show that Written-Pole motors have reliably operated in temperatures ranging from 42ºF to 122ºF.

• They may be operated safely in the open air if there is adequate protection from direct rain.The motor base must be mounted on a raised concrete pad or steel frame to avoid exposure to standing water.

A WRITTEN POLE RIDE THROUGH MOTOR USED IN A

FARM

APPLICATIONS

• Regulation of output voltage and frequency in electric generators,without relying on external regulators or power electronics.

• In a family of single and three-phase motive power and power protection systems used by many customers including the US Weather Service,NASA,Federal Aviation Authority,US Air Force and many commercial and industrial customers.

• To create a simple,rugged power protection unit combining Written-Pole motors and generators with an integral flywheel

AWARD WINNING TECHNOLOGY

• A recipient of the R&D 100 Award in 1994, Written-Pole technology was recognized by R&D Magazine as one of that year's most technologically significant innovations.

• The technology has also been recognized by numerous technical organizations including the Professional Society of Engineers in the United States.

CONCLUSION

• The written-pole motor, developed by Precise Power Corporation, is a motor design that allows for the operation of very large single-phase motors.

• This unique product has applications virtually anywhere that three-phase power is either not available, or is not economical to provide.

• This motor technology has the additional benefit of being able to ride through brief service interruptions on single-phase power lines.

WRITTEN POLE TECHNOLOGY

THANK

YOU!