FORMULATION OF PERMISSIBLE RADIAL DISTANCE BETWEEN DISTRIBUTION SUB-STATION AND RESIDENTIAL ELECTRICITY CONSUMERS

Abstract

One of the problems facing residential electricity power consumers in Nigeria is the effect of very low voltage at the consumers as a result of voltage drops on the distribution mains (low tension conductors) finding them

The consumers in the farthest distance to the supplying distribution substation usually experience low voltage as much as 100 volts as against a minimum terminal voltage of 216.2V or maximum voltage of 243.8V on a 230±6%V angle phase system.

This paper therefore carried out a research to determine an average permissible radial distance between the substation and the last consumer on a distribution line, where the consumer's terminal voltage does not fall below 216.2V

It came out with the following findings:

(a) That an Ammeter, Voltmeter and Energy meter be provided at every consumer's terminal, for load performance monitoring.

(b) That for a radial power distribution in residential areas, no load in excess of 20A per phase per house on a three-phase system, shall be connected. 

(c) The distance between the substation and last house on the distribution mains shall not exceed 500 metres.

(d)  The supply aluminium conductor per phase shall have a minimum of 70mm² cross-sectional area.

(e) The supplying transformer shall have a minimum of 500kva rating.

(f) The houses in the residential area may be a mixture of bungalow of 10 rooms or 2 flats and storey buildings of 4 flats per plot of land excluding high-rise structures.

(g) That when the total consumers load on a distribution line (mains) exceeds 160A phase to a point where the voltage is 216V, then table 4 in the main text can be employed to calculate the necessary radial distance to the substation, by plotting a graph of current against distance. Thereafter the appropriate distance can be found for a given total load current. Obviously, such distance shall be less than 500 metres.

With the adoption of the above measures, the consumers can:

• Enjoy electricity in their homes with good working appliances.
• Reduce cost of power installation and consumption.

The Power Holding Company of Nigeria Plc (PHCN) staff's job will greatly be simplified.