Handbook of Power Resistors (1959) -- Article Index

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Contents

SECTION 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

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Forward

Although 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.

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