scope:

This instruction sets out the methods of producing mean and peak current profiles, and the assumptions which have been made for the calculation.

Factors based on test results are included on both of the profiles to enable an assessment to be made of the current in any one track.

The instruction gives a method for producing profiles of mean and peak currents.

This instruction assumes that the traffic is typical of suburban and mixed traffic main line situations. Further consideration should be given on heavily loaded sections where the division of currents between tracks may differ from the typical factors.

This instruction does NOT cover the 25-0-25 kV autotransformer electrification system.

Purpose

Profiles of predicted mean and peak currents flowing in the overhead line are used by the Electrical Distribution Engineer to determine the rating of electrical equipment and by the Signalling and Telecommunications Engineer for electromagnetic interference studies.

The purpose of this document is to set out the methods followed when producing mean and peak current profiles for the 25 kV ac, 50 Hz overhead line electrification system.