Elements and Performance Criteria
- Explain how material properties affect resistance of electrical conductors
- Terms and symbols used in the formula for resistivity are used correctly
- How resistance varies with changes in conductor length and cross sectional area is outlined
- How resistance varies with temperature is outlined
- Calculations are performed that illustrate how material properties affect resistance of electrical conductors
- Apply Ohm’s Law to electrical circuits
- Main sources of EMF are identified
- Terms and symbols used in Ohm’s Law are used correctly
- Calculations are performed using Ohm’s Law to solve problems involving internal, external and variable resistances in both series and parallel circuits
- Calculations are performed to determine power required and /or energy expended by electrical devices
- Circuits for a wheatstone bridge and a slide wire bridge are sketched and their application on a ship is outlined
- Calculations are performed dealing with resistances, currents and voltage drops in bridge circuits under null or balanced conditions
- Apply principles of electrolytic action to electrical cells
- How the theory of electrolytic disassociation when applied to common electrolytic solutions and electrode materials explains the generation of EMF from chemical sources, is outlined
- Primary cells are distinguished from secondary cells
- Calculations are performed to solve problems involving currents, voltage drops and terminal potential difference of cells connected to form batteries in series and in parallel
- How capacity of a battery is measured is explained
- Construction of typical batteries used in marine environments is outlined
- Apply principles of electromagnetism to EMF generation
- Form and properties of the magnetic fields surrounding single conductor and multi-turn solenoid coils when carrying an electrical current are compared and contrasted
- Terms and symbols used in Faraday’s and Lenz’s laws of electromagnetic induction are used correctly
- Calculations are performed using Faraday’s and Lenz’s laws of electromagnetic induction to solve problems related to electromagnetism and EMF generation
- Fleming’s Right Hand Rule is outlined
- Explain operation of direct current rotating machinery
- Construction and methods of maintaining and repairing typical direct current (DC) machines are illustrated
- Principle wiring arrangements used with DC machines are outlined
- Action of the commutator in DC generators is outlined
- Significance of Back EMF (Eb) in the operation of DC motors is outlined
- Mathematical formula are applied to show relationships between operational parameters of DC motors
- Calculations are performed to solve simple problems relating to power output and efficiency in DC motors
- Explain operation of AC rotating machinery
- How three-phase AC may be developed out of simple single phase AC is explained
- Difference between Star and Delta connections is outlined
- How a three-phase supply can generate a rotating magnetic field is explained
- Construction of an AC synchronous generator is outlined
- Construction of an AC induction motor is outlined
- Calculations are performed to show how driving torque is produced in an induction motor
- Explain parallel operation and load sharing of generator
- Load/voltage curves of AC and DC generators are compared
- Main requirements for satisfactory power sharing between both AC and DC generators are outlined
- Sequences that occur when load changes on two DC generators working in parallel without an equaliser connection are outlined
- Effect of varying power factors on the load/voltage curve of an AC generator is outlined
- Apply Ohm’s Law to electrical circuits
- Main sources of EMF are identified
- Terms and symbols used in Ohm’s Law are used correctly
- Calculations are performed using Ohm’s Law to solve problems involving internal, external and variable resistances in both series and parallel circuits
- Calculations are performed to determine power required and /or energy expended by electrical devices
- Circuits for a wheatstone bridge and a slide wire bridge are sketched and their application on a ship is outlined
- Calculations are performed dealing with resistances, currents and voltage drops in bridge circuits under null or balanced conditions