EASA Electrical Engineering Handbook

FOREWORD

This portion of our site was provided by the Electrical Apparatus Service Association (EASA) and provided to you, produced in this format. The engineering reference information it contains was carefully selected to provide “Reliable Solutions Today” for your everyday use.

EASA is an international trade organization of electromechanical sales and service firms throughout the world. Through its many engineering and educational programs, EASA provides members with a means of keeping up to date on materials, equipment, and state-of-the-art technology.

When it comes to sales, application, service and maintenance of motors, generators, drives, controls and other electromechanical equipment, look to EASA and EASA members for “Reliable Solutions Today.” Only EASA members have the experience and professionalism to engineer energy-efficiency solutions for your complete motor system. To be assured of quality workmanship and performance, always look for the EASA logo.

The information in this section was carefully prepared and is believed to be correct, but EASA and Joliet Technologies, L.L.C. makes no warranties respecting it and disclaims any responsibility or liability of any kind for any loss or damage as a consequence of anyone’s use of or reliance upon such information.

Comments or questions about any of the data in this section may be directed to your local EASA sales and service center or to the Electrical Apparatus Service Association, Inc., 1331 Baur Blvd., St. Louis, MO 63132 U.S.A. or Joliet Technologies, L.L.C., 1724 Tomich Court, Crest Hill, IL 60403 (815) 725-9696.

Table of Contents

Motor Data – Electrical
Terminal Markings and Connections

Field Polarities of DC Machines

Maximum Locked-Rotor Currents – Three-Phase Squirrel Cage Motors
NEMA Code Letters For AC Motors
General Speed-Torque Characteristics

Effect of Voltage Unbalance on Motor Performance
Starting Characteristics of Squirrel Cage Induction Motors
Allowable Starts and Starting Intervals

Contractors
NEMA Size Starters for Three-Phase Motors
Starter Enclosures
NEMA Size Starters for Single-Phase Motors
Derating Factors for Conductors in a Conduit

Temperature Classifications of Insulation Systems
Resistance Temperature Detectors

Determining the Polarizatioin Index of Machine Windings

Useful Formulas and Conversions
Formulas for Electrical Motors
Formulas for Electrical Circuits
Temperature Correction of Winding Resistance
Motor Application Formulas

Glossary