7.1 Introduction

The sizes of generators and transformers, along with the voltage of the transmission line, have steadily increased since the commercialization of electrical power, to meet the ever-increasing demand. Networks at all levels of voltages are linked to make them rigid and reliable. The consequence of such a trend has resulted in ever-increasing fault levels on buses at generation, transmission, and distribution voltages. Disruption due to a short circuit fault in a network can have disastrous consequences leading to loss of life, property, and revenue.

All electrical equipment had to keep pace with their ability to withstand increasing fault levels. The impact has been most felt in the switchgear and Busbar Systems. Containing the increasing thermal, dielectric & electrodynamic stresses on electrical equipment in the industry has been a challenge. 

Continuous current rating of AC induction & arc furnace and DC metal extraction plants have also seen a phenomenal increase. 

Short circuit forces are an important parameter in the development and design of Busbar Systems. 

7.2 Forces

A current-carrying conductor produces a magnetic field. Another conductor in its vicinity carrying current will also produce a magnetic field. Their interaction will result in the conductors experiencing a force. In a Busbar System, rigid conductors (or for that matter, strung conductors in a transmission or switchyard) run parallel to each other and will experience a force depending upon…………………