NR/GN/ELP/27312
Impedances of 25 kV AC Overhead Lines for Classic System
Organization: | NR |
Publication Date: | 1 December 2006 |
Status: | active |
Page Count: | 32 |
scope:
The numbers provided in this document are based on a simplified representation of the impedances, which is suitable for manual calculations, for calculations undertaken by means of spreadsheets, and for use in the computer program 'OSLO'. This representation is not suitable for the Autotransformer system.
All of the provided numbers apply at the fundamental frequency, 50 Hz.
It is assumed that the users of this document understand the basic theory of electric circuits, including Ohm's Law, Kirchoff's First and Second Laws, and the use of complex numbers to represent the voltages, currents and impedances in an a.c. circuit.
Purpose
This Guidance Note contains information on the impedances of the 25 kV a.c. overhead lines and related items, for use by electrical design engineers who calculate line voltage drops or the settings of the feeder protection relays.