Motores

Table of Contents

Introduction ..............................................................................2 AC Motors ................................................................................4 Force and Motion .....................................................................6 AC Motor Construction ........................................................... 14 Magnetism.............................................................................20 Electromagnetism ..................................................................22 Developing a Rotating Magnetic Field ....................................28 Rotor Rotation.........................................................................34 Motor Specifications...............................................................39 NEMA Motor Characteristics ..................................................43 Derating Factors .....................................................................51 AC Motors and AC Drives .......................................................53 Matching AC Motors to the Load ...........................................58 Enclosures..............................................................................63 Mounting ................................................................................67 Siemens Motors ..................................................................... 74 Above NEMA Motors .............................................................79 Review Answers .....................................................................84 Final Exam..............................................................................85

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Introduction

Welcome to another course in the STEP series, Siemens Technical Education Program, designed to prepare our distributors to sell Siemens Energy & Automation products more effectively. This course covers Basics of AC Motors and related products. Upon completion of Basics of AC Motors you should be able to:• • • • • • • • • • • •

Explain the concepts of force, inertia, speed, and torque Explain the difference between work and power Describe the construction of a squirrel cage AC motor Describe the operation of a rotating magnetic field Calculate synchronous speed, slip, and rotor speed Plot starting torque, accelerating torque, breakdown torque, and full-load torque on a NEMA torque curveApply derating factors as required by an application Describe the relationship between V/Hz, torque, and horsepower Match an AC motor to an application and its load Identify NEMA enclosures and mounting configurations Describe Siemens Medallion™, PE-21 Plus™, vertical pump, and IEC motors Describe torque characteristics and enclosures of Siemens above NEMA motors

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This knowledge will help youbetter understand customer applications. In addition, you will be better able to describe products to customers and determine important differences between products. You should complete Basics of Electricity before attempting Basics of AC Motors. An understanding of many of the concepts covered in Basics of Electricity is required for Basic of AC Motors. You may also want to complete Basics ofControl Components which discusses the application of control devices for start, stop, and thermal protection of AC motors. If you are an employee of a Siemens Energy & Automation authorized distributor, fill out the final exam tear-out card and mail in the card. We will mail you a certificate of completion if you score a passing grade. Good luck with your efforts. Medallion and PE-21 Plus aretrademarks of Siemens Energy & Automation, Inc. National Electrical Code® and NEC® are registered trademarks of the National Fire Protection Association, Quincy, MA 02269. Portions of the National Electrical Code are reprinted with permission from NFPA 70-2002, National Electrical Code Copyright, 2001, National Fire Protection Association, Quincy, MA 02269. This reprinted material is not the complete...