PRESENTATION TOPICS Basics of Electricity Ohms Law Types of Electrical Circuits and Their Characteristics The Relationship Between Magnetism and Electricity Operating Principles of Electromagnetic Devices

ELECTRICITY:

The flow of electrons from atom to atom in a conductor.+++NNNN++NN+N+Protons: Positively ChargedNeutrons: Neutrally chargedElectrons: Negatively Charged------Conductor = Electrons easily dislodgedInsulator = Electrons NOT easily dislodgedSemi-Conductor = Neither good conductor nor insulator

CONDUCTOR: Allows electrons to easily flow from one atom to another. When the electrons flow from one atom to another electricity is produced.NucleusNucleusNucleusNucleusNucleusNucleus_

REPELS+ATTRACTSElectrons are dislodged by electrical charges which are either POSITIVE or NEGATIVEElectron Flow = CURRENTDifference between Positive and Negative = VOLTAGE-------

ELECTRICITY CONSISTS OF:Current: The flow of electrons through a conductor, measured in AMPERES. Amperes is the quantity of electrons flowing past a point in the circuit per second. 1 AMPERE = 6.28 BILLION ELECTRONS per Second!!!Voltage:The electrical pressure or force causing electrons to flow in a conductor, measured in VOLTS.The larger the difference between the positive and negative charges in a circuit the HIGHER the VOLTAGE.Resistance:Opposition to current flow, measured in OHMS. Created in a conductor by:The Resistance of the electron dislodging from its orbit around the nucleus The collisions of the electrons moving through the conductor.1 OHM resistance will allow 1 AMPERE to flow when 1 VOLT is applied to a circuit.

OHMS LAW: The amount of voltage, current and resistance in a circuit are related. Current in a circuit is directly proportional to the voltage applied and inversely proportional to the circuit resistance.

Stated as:

I = E/R

I is Current E is VOLTAGE R is RESISTANCE

8 Volts 4 AMPS = 2 OHMS8 Volts 2 Ohms = 4 AMPS4 Amps x 2 Ohms = 8 VOLTS

Electrical Circuits:A path for electron flow from a voltage source through the components and connectors and back to the source. An electrical circuit contains: A Voltage source (Battery, Alternator) A conductor that provides the path for current Electrical Components which provide resistance to flow (Switches, Resistors, Motors)

OPEN CIRCUITCLOSED CIRCUIT

CONVENTIONAL VS. ELECTRON THEORY:Conventional Theory: Electrons flow from the positive side of the terminal through the circuit to the negative terminal.

Electron Theory: Electrons flow from the negative terminal through the circuit to the positive terminal.

Electron Theory IS CORRECT, BUT Conventional Theory is the original and more common in everyday use.

SERIES CIRCUITPARALLEL CIRCUITPOP!POP!

SERIES/PARALLEL CIRCUITPOP!

CHARACTERISTICS OF A CIRCUIT:Series Circuit:Current Same at all points in the circuitVoltage Total Voltage equals sum of the voltage drops across each resistance.Resistance Total resistance equals sum of resistance in the circuit3 Ohms3 Ohms12 Volts2 Amps2 Amps2 Amps

CHARACTERISTICS OF A CIRCUIT:Parallel Circuit:Current Total Current is equal to the sum of current in all pathsVoltage Total voltage is the same is the voltage across each parallel pathResistance Total resistance is less than the resistance of any one path12 Volts3 Ohms3 Ohms4 Amps4 AmpsTotal Current = 8 AmpsTotal Resistance = 1.5 Ohms

CIRCUIT FAULTS:OPENSHORTGROUND

MAGNETS: A key component of electricity. Have a North and South pole Magnetic Lines of force extend from the north to south pole. Magnetic lines have direction but NO FLOW. Lines form a MAGNETIC FIELD Like poles repel / Opposite poles attractSN

MAGNETISM AND ELECTRICTY: Related through the phenomenon of ELECTROMAGNETISM When current flows through a conductor magnetic lines of force (flux) are created around the conductor The lines of force combine to form a magnetic field (More Current the stronger the field) Direction of current determines the direction of the lines of forceDirection of Magnetic field

COILS: When a conductor is wound in a coil, the electromagnetic fields combine creating one magnetic field with a north and south pole. Direction of current determines the direction of the electromagnetic field around the conductor and polarity of the magnetic field. The strength of the magnetic field depends on the number of loops of wire in the coil and the amount of current passing through.

More Loops OR Current = Stronger Magnetic Field.NSVoltage

ELECTROMAGNETS: When a coil is wound around an iron core it creates an electromagnet. The strength of the magnetic field is greatly increased because iron is a much better conductor than air. The iron core conducts the magnetic lines through the centre of the coreSNVoltage

RELAYS: A switch which is opened and closed by an electromagnet Iron Core can be stationary or moveableN/CN/CN/ON/ODE-ENERGIZEDENERGIZED

CONTACTORS: A larger relay, with heavy duty, high current capacity. Controlled by a low voltage circuit. Low voltage circuit CONTROLS High voltage circuits.Low Voltage ControlHigh Voltage OutputHeavy Duty Contacts

SOLENOID SWITCHES: Converts electrical energy into mechanical movement, (Starter). The metal core moves when the coil is energized. After the coil is de-energized the core is returned to its normal position by a spring.

SOLENOID VALVES: Operates in the same ways as the solenoid switch. Opens or closes a valve When energized the iron core shifts, core is part of the valve. After the coil is de-energized the core is returned to its normal position by a spring.

INTERLOCKS: Electrical contacts can also function as interlocks. A relay can control several interlocks simultaneously.Interlocks can be normally closed or normally open, referring to the position of the relay when NOT energized.Low Voltage InterlockHigh Voltage Contacts

CIRCUIT INTERLOCKS: Through interlocks relays can control multiple circuits at the same time and can set entire operating sequences into operation by energizing or de-energizing other relays.Low Voltage InterlockHigh Voltage ContactsSWITCH ActivatedRELAY Activated