WRITTEN-POLE ELECTRIC MOTORS

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WRITTEN-POLE ELECTRIC MOTORS

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

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CONTENTS

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

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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.

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AN INNOVATIVE PATENTED TECHNOLOGY

• In the 1990s, 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.

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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.

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CONSTRUCTION
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• 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.

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• 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.

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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
• .

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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
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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

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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.

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A WRITTEN POLE RIDE THROUGH MOTOR USED IN A FARM

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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

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AWARD WINNING TECHNOLOGY

• A recipient of the RD 100 Award in 1994,
  Written-Pole technology was recognized by RD
  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.

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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.

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THANK YOU!