2. Is a network of electrical components
used to supply, transmit and use electric
power.

3. The electric system is made up of an interconnected network of generating
plants, transmission lines and distribution facilities. Transmission lines, which
consist of heavy cables strung between tall towers, provide the transportation
highways to move electricity from generation sources to where the customer
uses it at a business or home or in a factory.
Transmission lines can vary from a few kilometres long in an urban environment
to thousands of kilometres for lines carrying power from remote power plants.
The transmission lines are interconnected with each other to form larger
networks, so that if one line should fail, another will take over the electric load.
Transmission lines can be overhead
or underground.
In most cases, the electricity carried on
transmission lines is alternating current
(AC), which travels more efficiently at
high voltages and can be easily
changed from low voltage to high
voltage, and vice versa.

4. 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).

5. Refrigerator pumps
aircon
machines
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.

6. 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.

7. 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.

9. 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

10. 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

11. 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