ABSTRACT
The evolution of low-current switch design has resulted in smaller devices with smaller operating forces and in the optimization of contact materials for particular applications. However, the reduction in size at a given current loading is limited by ergonomics; a hand-operated switch cannot be reduced in size to the point where the hand is unable to effectively operate the device. The size of a switch used to isolate a distribution voltage supply is also dominated by the need to maintain isolation distances between the conductors and also the need to switch both the live and neutral conductor simultaneously. The isolation requirement has a direct influence on the contact gap used in a switch, and as will be seen in Section 11.4, the gap will also have a direct effect on the switching dynamics as well as the arc erosion characteristic. There are generally three categories of contact gap, isolation gap, mini-gap, and micro-gap, and these are defined by international standards.
