Thermal transients and oil demands in cables

SINCE underground power cables almost always operate under variable loading, it is desirable toestablish their allowable carrying capacities on the basis of variable loading rather than upon thebasis of some equivalent steady state loading, as is the present practise. For this purpose it is most useful to know what temperature variations will occur at any point in the cable at any time due toan abrupt change from one constant load to another. Then any load curve can be handled with sufficient accuracy by breaking it up into a series of rectangular steps, and adding with proper time intervals the successive thermal transients