• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

PHYSICS –Power generation.

Extracts from this document...

Introduction

PHYSICS – Power generation

A generator requires a relative motion between a magnetic field and a coil. In power stations, an electromagnet is fed with a current to produce an induced EMF.

Electromagnetic induction refers to how magnetic fields can be used to produce electric currents and the effect caused if, either the force is applied externally or the magnetic field is changed.

When rotating a coil in a magnetic field, the flux through the coil varies as shown in a the below diagram:

    *

A representation of this variation is as follows:

    *

According to Faraday’s Law, induced EMF          E= -do/dt, which can be determined by the negative gradient of the previous graph.

Therefore induced EMF varies with times as follows:

    *

To provide a more even supply of power, generators are designed with three sets of coils, which produce three separate supplies of alternating current known as a three-phase generator. It is these three phases that are carried by the three conductors in the high voltage power lines we see coming from power stations.

Three-phase generators have three pairs of stator coils and an electromagnet set at 120º to each other.

    *

...read more.

Middle

AC can be readily switched by circuit breakers at any voltage, whereas switching of DC is only possible at the lowest voltages. AC motors and other electrical appliances are cheaper, simpler and more reliable.The frequency can be very precisely controlled and so AC is useful in motors which require accurate speed e.g. clocks, taper recorders, record players.AC can be easily and cheaply transformed up from generator voltages (typically 11-22kV) to main transmission voltages and down again to lower voltages as required.

The transmission system is required to transmit the electrical power generated in power stations to industrial, commercial and domestic customers.

Voltage is stepped-up by transformers

A transformer transforms electrical energy from one circuit to another by electromagnetic induction between two coils. The step-up transformer immediately increases the voltage to 400kV for transmission. In a step-up transformer, the number of secondary turns exceeds that of the primary coil and therefore the output voltage is greater than the input voltage.

The electrical power is given by, P=VI, where P = Power (P)

        V= Voltage (V)

        I = Current (I)

In-Line Cable transmission

Some of the power being fed into a transmission line is wasted before it reaches the consumer.

...read more.

Conclusion

The SEC charges a lower tariff for electricity used by off-peak appliances in order to level demands of power. In doing so it also saves enormous amounts of money because it reduces the number of power stations needed to meet each day’s peak demand for electricity. It also allows for maximum use of all plant, which is built. Examples of off-peak appliances include hot water services and heat banks. Such off peak appliances convert electricity into heat, which can be stores and used anytime during the day without adding to peak electricity demands.

It is important that SEC accurately forecasts demand for electricity because this way the public knows when to use electrical appliances at the correct time. If this is done incorrectly there could be many problems at power stations.

The fluctuating demand is met by Victoria’s hydro-electric plant and Snowy Mountains entitlement (as Victoria is entitled to one-third of production) as well as the gas turbine stations at Jeeralong in the Latrobe Valley and at Newport.

...read more.

This student written piece of work is one of many that can be found in our AS and A Level Electrical & Thermal Physics section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Electrical & Thermal Physics essays

  1. Peer reviewed

    Power generation

    4 star(s)

    Formation of oil: 1. Layers of the dead sea creatures settle on the sea beds 2. Layers of sedimentary rock build up on the top 3. The oxygen and pressure from these rocks, along with the absence of pressure, mean that oil is formed over millions of years.

  2. Single Phase Transformer (Experiment) Report.

    = 2886.40 V (Io)2 - (V1/rm)2 V 0.0732 - (160/3368.42)2 The lines on the graph involving the power loss and input power against the primary voltage are the same to one decimal place, which is not realistic. If power loss = power input then there would be no power output.

  1. Objective: To use a search coil and a CRO to investigate the magnetic ...

    shown on the CRO, i.e. the length of the vertical trace is the maximum, that means the magnetic field of the straight wire is the maximum. When placing the search coil at the end of the solenoid, across its cross-section, the induced e.m.f.

  2. Aim: To investigate the factors affecting the e.m.f. induced in a coil due ...

    The reading of the light-beam galvanometer should be kept constant at the value as in step 22. 25. The time taken for the current through the large solenoid reduced to zero was measured and recorded by the stop watch. The procedures were repeated 4 times and the mean time was taken.

  1. Characteristics of Ohmic and Non Ohmic Conductors.

    magnitude of current remains unchanged when the current or the voltage is reversed. The magnitude changes as displayed from the above graphs. The current is proportional to the voltage. The current is not proportional to the voltage. Temperature affects current and resistance.

  2. The aim of the experiment is to verify the maximum power theorem and investigate ...

    The contact surface does not affect the kinetic friction as the difference between the two ways of placing the wooden blocks is small. It can be neglected. The kinetic friction acted on the two blocks which was piled up is 2.6N while the two blocks which was placed side by side is also 2.6 N.

  1. The potato - a source of EMF

    4. Whenever the current reached the required value of mA the variable resistor was taken out of the circuit and put into the ohmmeter to read the exact load resistance, this value was then put into a column on the data table.

  2. Electricity generation from renewable and non-renewable sources.

    1. Less air pollution than fossil fuel 2. Lower Co2 emission than fossil fuel 3. Moderate environmental impact 1. Lacks portability 2. Releases CO2 when burned 3. Extraction side effects Nuclear In most electric power plants, water is heated and converted into steam. In a nuclear power plant; the fission of uranium atoms in the reactor provides the heat to produce steam for generating electricity.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work