JSS 3, TOPIC 1: TRANSMISSION OF ELECTRICITY AT LOW FREQUENCY

Definition: Transmission of electricity deals with the production (generation), distribution and utilization of electricity in a particular region of a country.

Production of Electricity: This is the act of generating electricity from a particular location by the use of generators, turbines, gas and water (hydro).
Distribution of Electricity: This refers to the injection of electrical power into villages, towns and cities through sub-stations.

Utilization of Electricity: This is the process of putting electricity to optimum  use in households, commercial centers and industries.

Transmission of electricity at low Frequency.

In Nigeria, electricity is transmitted at low frequency but at high voltage. This is measured at 50Hertz(Hz) per second. Transmission is usually in alternating current principle. PHCN generates power at 11KVA and it is steeped up to 132KVA so that each station is connected to a common grid called the National grid.

                    Equipment Used in the Transmission of Electricity at Low Frequency.

(i). Generation Control Panels: This is the location where power is generated at power stations by many generators connected to a common 3-phase panel to obtain a common frequency.
(ii). Sub-Station: This is a place outside the power station for the conversion, transformation and control of electric power.
(iii). Circuit breaker: This equipment is used to make and break the flow of current to protect against earth leakages and overload current (especially during maintenance).
(iv). Transformer: They are used for stepping-up and stepping-down of electrical voltages.
(v). Transmission lines: These are aluminum cables used in power transmission.
(vi). Line support: These are the poles that carry the overhead lines.
(vii). Insulators: Insulators bond the overhead lines from the poles to avoid electrocution by anyone who may touch the poles. There are different types namely the pin, strain and the suspension types.
(viii). Lightning arrestor: This equipment arrests lightning surges that creates over voltage to the lines so as to protect the lines.
(ix).Fuses: Fuses are used to protect the lines in the event of over- voltage or current. In the event of spark, the fuse melts and drops.
(x). R.M.U. This simply means Ring Main Unit. It is the equipment used in separating feeders to an area.

                                             Power Transmission system diagram 

REVIEW QUESTIONS

1. List 5 equipment used during electricity transmission in Nigeria.
2. State one advantage of the lightning arrestor in electricity transmission.3. Define the following terms:
(a).transmission of electricity
(b).production of electricity