Table of Contents

FOREWORD
INTRODUCTION
Section 1: General
1 General
  1.1 Scope and object
  1.2 Reference documents
  1.3 Definitions
  1.4 Symbols
Section 2: Theory
2 General considerations concerning the nature of
  electric contact and the calculation and
  measurement of the ohmic resistance of contacts
  2.1 Electric contacts and connection terminals
  2.2 Nature of electric contact
  2.3 Calculation of contact resistance
3 Ageing mechanisms of contacts and connection terminals
  3.1 General
  3.2 Contacts of dissimilar metals
  3.3 Oxidation ageing mechanisms
  3.4 Results concerning ageing of copper contacts
  3.5 Usage and precautions to be taken in the use of
      contact materials
4 Calculation of temperature rise of conductors, contacts
  and connection terminals
  4.1 Symbolic representations
  4.2 Temperature rise deltaT[s] of a conductor with respect
      to the temperature T[e] of the surrounding medium
  4.3 Temperature rise deltaT[o] o in the vicinity of the
      contact: temperature rise of connection terminals
  4.4 Temperature rise of the elementary contact points
Section 3: Application
5 Permissible temperature and temperature rise values
  5.1 Ambient air temperature theta[a]
  5.2 Temperature and temperature rise of various
      equipment components
  5.3 Temperature and temperature rise of conductors
      connecting electrical equipment
  5.4 Temperature and temperature rise of connection
      terminals for electrical equipment - Influence
      on connected conductors
6 General procedure to be followed for determining
  permissible temperature and temperature rise
  6.1 Basic parameters
  6.2 Method to be followed for determining maximum
      permissible temperature and temperature rise
Annex A - Numerical examples of the application of the
          theory and other data
Annex B - Physical characteristics of selected metals
          and alloys
Annex C - Physical characteristics of fluid dielectrics
Annex D - Information on the reaction of contact metals
          with substances in the atmosphere
Annex E - Temperature rise of a conductor cooled by
          radiation and convection in the vicinity
          of a terminal
Annex F - List of symbols used in this report
Annex G - Bibliography

Abstract

Provides guidance in estimating the permissible values for temperature and temperature rise of component parts of electrical equipment carrying current under steady state conditions.

General Product Information

Published
Document Type	Standard
Status	Current
Publisher	International Electrotechnical Committee
Pages
ISBN
Committee	TC 32
Supersedes	IEC 943 : 1ED 89