PD 6524:1989

National foreword
Committees responsible
Guide
Introduction
1. General considerations
1.1 Scope
1.2 Object
2. General considerations concerning the nature of
     electric contact and the calculation of the ohmic
     resistance of contacts
2.1 Electric contacts and connection terminals
2.2 Calculation of contact resistance
3. Ageing mechanism 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 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 Definitions
4.2 Temperature rise delta Ts of a conductor with
     respect to the temperature Te of the surrounding
     medium
4.3 Temperature rise delta T0 in the vicinity of the
     contact: temperature rise of connection terminals
4.4 Temperature rise of the elementary contact points
4.5 Numerical example
5. Permissible temperature and temperature rise values
5.1 Definitions
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
6.3 Chart for determining maximum permitted temperature
     or temperature rise
References
Appendix A: Characteristics of selected metals and alloys
Appendix B: Physical characteristics of certain
dielectrics
Appendix C: Information on the reaction of contact metals
with substances in the atmosphere
Appendix D: Bolted (screwed) terminals and connections:
recommended clamping torques
Appendix E: Insulation classes
Appendix F: List of letter symbols used
Appendix G: Derivation of an equation representing the
temperature rise of a conductor in the vicinity of a
terminal, in the case of cooling by radiation and natural
convection

Applies, in particular, to switchgear contacts and connection terminals.