Is a network of electrical components

used to supply, transmit and use electric

power.

The electric system is made up of an interconnected network of generatingplants, transmission lines and distribution facilities. Transmission lines, whichconsist of heavy cables strung between tall towers, provide the transportationhighways to move electricity from generation sources to where the customeruses it at a business or home or in a factory.Transmission lines can vary from a few kilometres long in an urban environmentto thousands of kilometres for lines carrying power from remote power plants.The transmission lines are interconnected with each other to form largernetworks, so that if one line should fail, another will take over the electric load.Transmission lines can be overheador underground.In most cases, the electricity carried ontransmission lines is alternating current(AC), which travels more efficiently athigh voltages and can be easilychanged from low voltage to highvoltage, and vice versa.

Electric power is the mathematical

product of two quantities:

Current and voltage

These two quantities can vary

with respect to time

(AC power) or can be kept at constant levels

(DC power).

Refrigerator pumps

machinesaircon

use AC power whereas most computers and digital equipment use

DC power (the digital devices you plug into the mains typically have

an internal or external power adapter to convert from AC to DC

power). AC power has the advantage of being easy to transform

between voltages and is able to be generated and utilized by

brushless machinery.

the ability to easily transform the voltage of AC power is

important for two reasons: Firstly, power can be transmitted

over long distances with less loss at higher voltages.

So in power systems where generation is distant from the

load, it is desirable to step-up (increase) the voltage of power

at the generation point and then step-down (decrease) the

voltage near the load.

Secondly, it is often more economical to install turbines

that produce higher voltages than would be used by

most appliances, so the ability to easily transform

voltages means this mismatch between voltages can be

easily managed.

Electric Power system

Select the best answer: page 8 of 10

Question 1 of 3

Two quantities can vary with respect to time (AC power) or can be kept at constant levels (DC power)?

a. resistance and current

b. current and voltage

Electric Power system

Select the best answer: page 9 of 10

Question 2 of 3

Alternating current power is typically supplied by a rotor that spins in a magnetic field in a device known as a?

a. turbo generator

b. generator

Electric Power system

Select the best answer: page 10 of 10

Question 3 of 3

Smaller power systems are also found in industry, hospitals, commercial buildings and homes. The majority of these systems rely upon?

a. single – phase AC power

b. three – phase AC power