BS 7450:1991

This standard BS 7450:1991 Method for determination of economic optimization of power cable size is classified in these ICS categories:

• 29.060.20 Cables

This International Standard deals solely with the economic choice of conductor size based on joule losses. Voltage dependent losses have not been considered.

NOTE 1 It is recommended that the method given in this standard should not be used for cables operating on system voltages equal to or greater than the following (see IEC 287):

Type of cable	System voltage Uo kV
Cables insulated with impregnated paper:
solid type	38
oil-filled and gas pressure	63,5
Cables with other types of insulation:
butyl rubber	18
EPR	63,5
PVC	6
PE (HD and LD)	127
XLPE (unfilled)	127
XLPE (filled)	63,5

NOTE 2 Modifications to the method given in this standard in order to take dielectric losses into account are under consideration.

Likewise, matters such as maintenance, energy losses in forced cooling systems and time of day energy costs have not been included in this standard.

An example of the application of the method to a hypothetical supply system is given in Annex A.

For economic choice of conductor size based on joule losses. Voltage dependent losses are not considered.