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Elements and Performance Criteria

1. Apply concepts of resistivity, resistance and capacitance to series and parallel AC and DC circuits
   • Calculations are performed to solve problems related to resistance, voltage drop, current and power in series and parallel circuits
   • Calculations are performed to solve problems related to temperature coefficient of resistance and change of resistance of a conductor with a change of temperature
   • Basic relationships that give total equivalent capacitance for capacitors arranged in series and parallel combinations are derived
   • Relationships that give total equivalent capacitance to solve numeric problems involving alternating current (AC) and direct current (DC) circuits are applied
2. Explain how principles of electrolytic action apply to electrical cells and batteries
   • Kirchhoff’s circuit laws are explained
   • Calculations to solve problems involving currents, voltage drop and terminal potential difference for cells connected to form batteries in series and in parallel are performed
   • Calculations to solve secondary cell charging and discharging problems are performed
   • Calculations to solve problems related to the efficiency of cells are performed
3. Analyse a magnetic circuit
   • Key parameters of magnetic circuits are identified
   • Formula for calculating the amount of flux generated by a multi turn solenoid coil carrying a current to give the B/H relationship is applied
   • Significance of the varying slopes in the B/H curves for a solenoid coil with air, cast iron, cast steel and mild steel cores is explained
   • How a magnetic circuit may be created by using a toroidal core within the solenoid coil is demonstrated
   • Calculations to solve problems relating to magnetic circuits using different materials in different parts of their cores, including air gaps, are performed
   • Effect on flux density of applying an alternating magnetising force to an iron core is shown diagrammatically
4. Interpret electromagnetic consequences of a conductor moving relative to a magnetic field
   • Faraday’s and Lenz’s Laws are applied to solve problems relating to the electromagnetic induction of EMF and current
   • Generation of EMF is illustrated by a simple, single loop conductor rotating in a uniform magnetic field and how this EMF may be tapped to an external circuit as either AC or DC is explained
   • How alternating electrical quantities may be represented by rotating phasors is illustrated and explained
   • Relationships between instantaneous, maximum, average and RMS values of sinusoidally alternating electrical quantities is derived
   • Mathematical problems are solved by applying relationships between instantaneous, maximum, average and RMS values of sinusoidally alternating electrical quantities
5. Analyse circuits that incorporate combinations of resistive, inductive, and capacitive elements
   • Time constant for different circuit combinations subjected to DC EMF’s is defined
   • Calculations are performed to solve problems involving time constants in DC circuits with changing rates of current in resistive/inductive elements and changing voltages through resistive/capacitive circuit elements
   • Differentiation is made between inductive reactance, capacitive reactance and impedance as applied to AC circuits
   • Effects of inductive and capacitive reactance upon phasor relationships between applied AC voltage and current are shown
   • Concept of total impedance is applied to solution of problems involving single phase AC quantities in the presence of both resistive/inductive and resistive/capacitive circuit elements, arranged in either series or parallel
   • Power factor is defined and concepts of real and reactive power usage are applied to solution of problems involving RL and RC elements
6. Analyse operation of polyphase AC circuits
   • How three phase AC may be developed out of simple single phase AC is explained
   • Voltage and current relationships between line and phase in both Star and Delta 3 phase connections are derived
   • Standard Star to Delta and Delta to Star conversion relationships for current and voltage are derived
   • Numeric problems involving both balanced and unbalanced circuit loads are solved
   • Relationships between kW, kVA and kVAr for 3 phase AC circuits is derived
   • Calculations are performed using the relationship between kW, kVA and kVAr to solve problems in 3 phase AC circuits
7. Describe basic operating principles of shipboard DC machinery
   • Schematic circuits are prepared for separately excited, series, shunt and compound connected generators and motors to illustrate wiring arrangements used with DC machines
   • EMF equation for a DC generator to solve shipboard problems is applied
   • Torque equation for a DC motor to solve shipboard problems is applied
   • Expression linking back EMF parameters for a DC motor is derived and used to solve shipboard problems
   • Various losses that can occur in DC motors and generators are calculated
8. Perform calculations related to operation of AC generators
   • Construction features of the AC synchronous generator are explained
   • EMF equation for an AC generator is derived, taking into account distribution and pitch factors
   • Expression for the magnitude and speed of the rotating flux generated by a three-phase supply is derived
   • Voltage regulation for synchronous generator is defined
   • Effect of power factor on load characteristic of an AC generator is illustrated
9. Perform calculations related to operation of three-phase AC induction motors
   • Construction features of the AC induction motor are explained
   • Expression for slip of an induction motor rotor is derived and applied to frequency of its rotor EMF and current
   • Expression for magnitude of rotor EMF and current is derived, taking into account distribution and pitch factors
   • Relationships between rotor torque, rotor losses and slip indicating factors that affect torque are outlined
   • Significance of torque/slip curves for an induction motor is explained
   • Relationship between starting torque and applied voltage is established and consequences of this upon starting methods are outlined
10. Explain operating principles of basic electrical instrumentation
    • Schematic circuit diagrams are prepared that illustrate the main features and applications of moving coil and moving iron voltmeters and ammeters
    • Schematic circuit diagrams are prepared that illustrate the main features and applications of air and iron cored dynamometer type wattmeters
    • Dangers associated with current and voltage transformers on high current and voltage systems are identified

Range Statement

Range is restricted to essential operating conditions and any other variables essential to the work environment.
Key parameters of magnetic circuit include one or more of the following:	current flux flux density magnetising force magneto motive force
Circuit combinations must include:	resistive/capacitive resistive/inductive
Losses include one or more of the following:	copper losses iron losses or magnetic losses mechanical losses

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Performance Evidence

Evidence required to demonstrate competence in this unit must be relevant to and satisfy all of the requirements of the elements, performance criteria and range of conditions on at least one occasion and include:

applying relevant work health and safety/occupational health and safety (WHS/OHS) requirements and work practices assessing own work outcomes and maintaining knowledge of current codes, standards, regulations and industry practices identifying and applying relevant mathematical formula and techniques to solve problems related to marine electrotechnology identifying and interpreting numerical and graphical information, and performing mathematical calculations such as the relationship between starting torque and applied voltage in three phase AC induction motors identifying, collating and processing information required to perform calculations related to marine electrotechnology performing accurate and reliable mathematical calculations using a calculator reading and interpreting written information needed to perform intermediate electrical calculations solving problems using appropriate laws and principles.

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Knowledge Evidence

Evidence required to demonstrate competence in this unit must be relevant to and satisfy all of the requirements of the elements, performance criteria and range of conditions and include knowledge of:

AC induction motors AC principles batteries circuit diagrams DC motors difference between AC and DC effective verbal, written and visual communication strategies electrical: current power units of measurement electromagnetic: force induction Faraday’s and Lenz’s Laws of Electromagnetic Induction intermediate electrical circuits intermediate principles of marine electrotechnology Kirchhoff’s circuit laws magnetic circuits National and international maritime regulations, IMO Conventions and Codes applicable to the operation of electrical and electronic control equipment on vessels of typically unlimited propulsion power Ohm’s Law polyphase AC circuits principles of: electrical safety electrolytic action electromagnetism parallel circuits principles and procedures for electrical and electronic measurement series circuits shipboard DC machinery WHS/OHS requirements and work practices.

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