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ContentsSECTION I. GENERAL RESISTOR CONSIDERATIONS Basic Definitions Performance Standards Wire or Ribbon Power Type Resistors 4 Basic Power Resistor Functions 4 Fundamental Resistance Calculations 5 Ohm's Law Kirchoff's Laws Wire Resistance SECTION II. MATERIALS FOR RESISTORS General Construction Resistive Conductors Resistivity, Temperature Coefficient of Resistance Mechanical Strength, Maximum Working Temperature, Corrosion Aging, Temperature Coefficient of Expansion Resistive Conductor Supports Terminals Protective Coatings Thermal Conductivity, Radiation and Convection Thermal Shock, Thermal Expansion, Mechanical Protection, Corrosion Insulation SECTION III. TYPES OF RESISTORS Vitrohm Tubular Resistors Construction Forms, Terminals Mountings Enclosures Ratings, Resistance Tolerance Performance Data Application Data Strip-ohm Resistors Construction Methods of Mounting, Ratings Performance Data, Application Data Vitrohm Kon-Inductive Resistors Construction Terminals, Mountings, Ratings, Performance Data, Application Data, Effects of Frequency Plaqohm Resistors Construction Mountings Ratings Performance Data, Application Data Discohm Resistors Construction, Methods of Mounting, Ratings Ribflex Resistors Construction, Terminals, Mountings Ratings Performance Data, Application Data, Intermittent-Duty Ratings Edgeohm Resistors Construction, Mountings Ratings, Performance Data Application Data, Intermittent-duty Ratings Group Ratings Barohm Resistors Construction Mountings, Ratings, Performance Data, Application Data Loopohm Resistors Construction. Mountings, Ratings Performance Data Application Data Special Types of Resistors Channel-type Resistors Sandbox Resistors Coiled-wire Resistors Ribohm Resistors SECTION IV. CRITERIA FOR SELECTION Introduction Guide for Resistor Selection Load Versus Temperature Rise Curves Derating Curves for Various Ambients Derating Curve for Various Altitudes Derating Curve for Grouping Resistors Derating Curve for Enclosures Intermittent-duty Curves Thermal Capacity Maximum Voltage Limitations Surge Voltage of Steep Wave Front Ratings Versus Number of Taps Abnormal Operating Conditions SECTION V. STANDARD TYPES AND SIZES OF RESISTORS Axiohm Resistors Vitrohm Tubular Resistors Stripohm Resistors Vitrohm Non-Inductive Tubular Resistors Plaqohm Resistors Discohm Resistors Ribflex Resistors Edgeohm Resistors Barohm Resistors Loopohm Resistors Terminals SECTION VI. THE MAKING OF A VITROHM RESISTOR SECTION VII. RESISTOR STANDARDS NEMA Standards SECTION VIII. DEFINITIONS USEFUL DATA; BIBLIOGRAPHY and REFERENCES Conversion Factors Drill Sizes for Machine Screws Gauges for Wire, Sheet and Twist Drills Electrical, Mechanical and Heat Equivalents Temperature Conversion Table Full Load Motor Currents Mechanical Functions and Electrical Analogs Symbols for Power, Control and Measurement ++++++ ForwardAlthough the history of resistor manufacture dates back to the discovery of electricity, detailed information on power resistor construction and characteristics still remains the property of a few specialists. The literature of the electrical industry has treated other control components in copious detail. Power resistors, perhaps the most common of all, have probably for this very reason suffered from neglect. This handbook represents an effort to present a more comprehensive analysis of the construction of power resistors, and their application and performance characteristics. The material herein presented stems from more than half a century of practical design and manufacturing experience by the Ward Leonard Electric Co. and represents the collective effort of its sales and engineering staffs. Because the applications of power resistors are so broad in scope, an extended analysis of specific application problems has not been attempted in this edition. It is our hope that this handbook will aid in promoting a broader understanding of power resistor construction and characteristics and serve as a helpful guide to the student, application engineer, and equipment manufacturer interested in the subject. A. A. BERARD; President Ward Leonard Electric Co. +++ Also see: 101 ways to use your OSCILLOSCOPE (1974) +++ |
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