1. 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

3. LIMITATIONS OF CONVENTIONAL TECHNOLOGY
1.Dependence of speed on no. of poles of rotor.
speed = 120 X frequency
no. of poles
2.The machine must have even no. of poles and deviating from this condition will cause unstability at its rated speed.

4. 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.

5. 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.

6. CONSTRUCTION

7. 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.

8. 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.

9. 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 .

10. 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

11. ADVANTAGES 1. Low starting current requirements
2. Energy efficient operation
3. Unity power factor operation
4. Simple construction
5. Low temperature rise
6. High inertia starting
7. Instantaneous restart capability
8. Ride through characteristics
9. Three-phase applications

12. 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.

13. A WRITTEN POLE RIDE THROUGH MOTOR USED IN A FARM

14. 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

15. 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.

16. 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.

17. WRITTEN POLE TECHNOLOGY
THANK YOU!
WRITTEN POLE TECHNOLOGY