The cyclic rating of a single three-core cable or a group of equally loaded identical cables located in a uniform soil requires computation of a cyclic rating factor M by which the permissible steady-state rated current (100% load factor) may be multiplied to obtain the permissible peak value of current during a daily (24 h) cycle such that the conductor temperature attains, but does not exceed, the standard permissible maximum temperature during the cycle. A factor derived in this way uses the steady-state temperature, which is usually the permitted maximum temperature, as its reference. The cyclic rating factor depends only on the shape of the daily cycle, and is independent of the actual magnitudes of the current.

.$I_{\mathrm{c_{\mathrm{peak}}}}$

A

$I_{\mathrm{c}} M$

$M$

Cyclic rating factor [p.u.]