Week 9 (a)

   (A)Principle of electricity

1.      Atomic Theory

 ·         An atom is made up of protons (+ charge), neutrons (no charge) and electrons (- charge)

 ·         If an atom has the same number of electrons and protons, it will be balanced and have a neutral charge.

 ·         If an atom has more than one electrons than protons, it will be unbalanced and will be negatively charged.

·         If an atom has more protons than electrons, it will be positive charged

2.Electron flow

  ·         A length of electrons from each atom forced out of their orbit.

  ·         These electrons capable of moving to another atom.

  ·         Electrons flow from negative terminal towards positive terminal of the power supply through an electrical circuit.

  ·         Atoms on the positive side have a deficiency of electrons, so they are positively charged.

  ·        Atoms on the negative side have an access of electrons, so they are negatively charged.

3.Current flow

 

·         Current was flow through a conductor from positive to negative

·         Electrons move in opposite direction

4.     Electricity

Static electricity 

·         an electrical charge builds up on the surface of an object.

·         charges remains at rest they don’t move.

·         the charges required by rubbing of silk cloth.

Current electricity 

·         electricity comes from a power source such as battery.

·         charges are in motion.

·         the electricity used in our home is current electricity

5.    Circuit

        Series Circuit

 

·         has two or more loads connected, one after another.

·         has only one path it can flow along

     Parallel Circuit

        

      ·         has more than one path the current can flow on.

      ·         removing or adding loads to a parallel circuit does not affect any other load in the circuit

   Combination circuit

           ·         combine series circuit and parallel circuit

6. Circuit condition

            Open circuit is the wires are cut off so there will be no current flow.

Closed circuit is the wires are connected so there will be flow of current.

  Short circuit is original path of current flow is altered and a “shorter” than normal path

  for current flow exists.

7.     Terminology

(B)How VIR Is Connected?

Current, voltage and resistance are connected by Ohm’s Law.

‘Current flow in a circuit is directly proportional to the voltage across the circuit and inversely proportional to the resistance contained in the circuit, providing circuit conditions remain the same’

Ohm’s law can be stated in simplest and mathematical way.

·         If voltage of a circuit increase, current (flow of electron) increase as well.

·         If resistance of a circuit is increased, the current flow will decrease in direct proportion.

(C)Power Generation

Sources of electromotive force

1.Chemical

·         uses chemical effects to produce electromotive force

·         achieved by placing two dissimilar metals into an electrolyte.

2.Light

·         sun’s ray can be used to produce a voltage potential.

·         achieved by using a solar cell

·         solar cell is a thin junction made of two different types of semiconductor materials.

3.Magnetism

·         most common way

·         when a conductor passes through a magnetic field, cutting through the invisible lines of flux, a voltage is induced into the conductor.

(D)A power generation plant is a facility designed to produce electric energy from another form of energy, such as:

1.Solar Power Generation

·         Uses Photovoltaic (PV) cells which converts sunlight into electricity.

·         This is done by using solar panels, which are large flat panels made up of many individual solar cells.

·         Used in remote locations.

2.Hydro-Power Generation

·         One of the alternative energy sources

·         Uses gravitational potential energy of water as fuel

3. Coal Power Generation

·        Use coal as fuel

·        Coal is first milled to a fine powder, which increases the surface area and allows it to burn more quickly.

4. Nuclear Power Generation

·         A nuclear reactor produces and controls the release of energy from splitting the atoms of uranium.

·         Uranium-fuelled nuclear power is a clean and efficient way of boiling water to make steam which drives turbine generators

(E)Electrical transmission & distribution

 (F) System Involved

1.       Transmission system

·         Dissemination of electrical energy from power plant to high-voltage station.

2.  Distribution system

·         Distribution of electrical energy from high-voltage station to consumer fit-out source.

      (G)  Type of Phase in Electricity

1.      Single Phase

·         Generated by rotating a single turn coil through a magnetic field.

·         The phase of the waveform produced by a generator such as the alternator is in the form of sine wave.

·         Wire used: 

ü  Live conductor (yellow)

ü  Neutral conductor (blue)

ü  Earth conductor (green): connected from via a protective gear to eart.

·         Three conductors (lines) to carry the three phase supply, coloured red, yellow and blue.

·         A fourth conductor called the neutral, connected through protective device to earth.

·         Three phase systems usually connected using:

   ü  Star connection as a source which is alternator

   ü  Delta connection such as transformers, motors and other loads

Case Building: Electrical System in Dewan Sultan Iskandar

1.Generator

2. Miniature circuit breaker