The term Insulation Co-ordination was originally introduced to arrange the insulation levels of the several
components in the transmission system in such a manner that an insulation failure, if it did occur, would be
confined to the place on the system where it would result in the least damage, be the least expensive to repair,
and cause the least disturbance to the continuity of the supply. The present usage of the term is broader.
Insulation co-ordination now comprises the selection of the electric strength of equipment in relation to the
voltages which can appear on the system for which the equipment is intended. The overall aim is to reduce to
an economically and operationally acceptable level the cost and disturbance caused by insulation failure and
resulting system outages.