Current and Temperature Rise in Aircraft Cables: Part II Uniform Bundles Under Steady-State Conditions

The steady-state relations between current and temperature rise for single cables in air were described in NRL report No 3587 as a first step toward the solution of the bundle-rating problem. As the second step an empirical study of the continuous current capacity of aircraft cables in uniform bundles (bundles composed of the cables of a single size) was undertaken. The investigation of the effects on current capacity of (1) the number of cables loaded simultaneously, (2) the position of the loaded cables in the bundle, (3) the total number of cables in the bundle, and (4) the spacing between adjacent cables, shows that a set of minimum conditions can be defined to serve as a basis for rating cables in uniform bundles. The study shows that an approximate analysis of the heat flow in the bundle is possible. Application of this analysis to the calculation of currents for cables in uniform bundles results in values which differ by less than five percent from measured currents.