Electric PowerJye Perry

A.C. Electricity Generation A.C. electricity generation is the generation of

electricity by moving a metal wire through a magnetic field

The change in magnetic flux through the wire induces an alternating current that is proportional to the mechanical energy input into the rotation of the wire frame

Methods of electricity generation in Victoria

Solar Energy Solar power is the conversion of the energy

in sunlight into electricity using a photovoltaic power system which produces a direct current

The direct current produced is fed into an inverter which converts it onto an alternating current at the desired frequency which can be used by conventional household appliances or sent back into the power grid

Transmission Map Vic

Transmission Lines The conductor material is an aluminium

alloy, made into several strands and reinforced with steel strands

While it has more resistance than copper it is cheaper, stronger and more durable

Transformers Transformers are and important aspect in an

electrical system because they increase and decrease the voltages within the circuit for long distance transmission

This allows for less electricity to be lost in the circuit while the electricity is carried great distances from power generating plants to towns and cities

Before the electricity enters a house the voltage is decreased to the appropriate 240V for which most household appliances use

Q3 - Town Voltages P = VI so I = P/v Current = 220,000/5500 = 40A Power Loss = I^2R = 40^2 x 4 = 6,400W 220,000W – 6,400W = 213,600W Voltage in town = 213,600 = V x 40, V = 5340V 220,000 = 110,000 x I, I = 2A Power Loss = 2^2 x 4 = 16W 220,000W – 16W = 219,984W 110,000/5500 = 20 : 1 turns

High Voltages in the Transmission System

In an electrical circuit the power loss is defined by the formula Power Loss = Current^2 x Resistance which also applies to power lines

Energy is lost in power lines as heat due to the resistance in the conductors and so reducing the current in the lines reduce this heat loss and is more effective in reducing power loss than reducing the resistance itself

The Human Body and Electricity Electric shock occurs when contact is made between two

points of a circuit causing electricity to pass through the body

An electrical injury has many consequences to a body as the electrical currents can travel through the nervous system and burn out tissue in patches along the way

This can leave bizarre symptoms anywhere on the body and may lead to complex regional pain syndrome

Electricity's effectCurrent Intensity(one second duration)

Effect

1 mAmpere Threshold of perception

5 mAmperes Accepted as maximum harmless current intensity

10-20 mAmperes Victim can still let go; sustained muscularcontraction not yet a problem

50 mAmperes Pain, strong muscular contraction; can’t let go;possible fainting, exhaustion. Heart and respiratoryfunctions continue

100-300 mAmperes Ventricular fibrillation can start; respiratoryfunctions continue

6 Amperes Temporary cardiac and respiratory interruption;burns occur

> 20 Amperes Severe burns; physical dismemberment at highercurrents

Safety Features in Households A safety switch is intended to trip out an electricity supply in

the event of a current flow to earth. It can provide protection from harmful electric shocks in situations where a person comes into contact with a live electrical circuit and provides a path to earth

A circuit breaker is an automatically operated electrical switch designed to protect an electrical circuit from damage caused by overload or short circuit. Its basic function is to detect a fault condition and interrupt current flow. Unlike a fuse, which operates once and then must be replaced or reset

Load Curve A load curve is a graph of the variation in the

electrical load versus time. It varies according to customer type (residential, commercial and industrial), temperature and holiday seasons

It is used to plan how much electricity is needed to be made available at any given time

Energy used for a Typical Summers Day

7,000MW x 24H = 168,000MW/H 168,000 x 3.6x10^9 = 6.05x10^14J