MARL038 — Apply advanced principles of marine electrotechnology

1 Analyse circuits incorporating resistance, inductance and capacitive elements in alternating current (AC) and direct current (DC) circuits

• 1.1Mathematical problems involving resistor inductor (RL) and resistor capacitor (RC) combinations in DC circuits are solved
• 1.2Mathematical problems involving resistive, inductive and capacitive reactance and overall circuit impedance in AC circuits are solved
• 1.3Reasons why large power factors are desirable in AC circuits are explained
• 1.4Mathematical problems related to power factor correction mechanisms are solved
• 1.5Conditions for resonance in series and parallel RLC circuit combinations are analysed
• 1.6Mathematical problems involving resonance in series and parallel RLC circuit combinations are solved
• 1.7Calculations are performed to solve problems related to solve resistance, voltage drop, current and power in series and parallel circuits
• 1.8Calculations are performed to solve problems related to temperature coefficient of resistance and change of resistance of a conductor with a change of temperature

2 Apply complex number theory to analyse AC circuit performance

• 2.1J operator is explained
• 2.2Rectangular notation of j operator is related to comparable trigonometric and polar notations
• 2.3J operator is used in the addition and subtraction of phasors, applying the most appropriate notation to the solution of phasor problems involving current, voltage and impedance
• 2.4Conductance, admittance and susceptance are distinguished from each other in terms of resistance, impedance and the j operator
• 2.5Problems involving RL and RC elements in different circuit combinations using j operator theory are solved
• 2.6Power in AC circuit applications using j operator theory is calculated

3 Analyse operating principles of electrical instrumentation

• 3.1Mathematical calculations are performed to demonstrate how moving coil and moving iron instruments may have their ranges changed
• 3.2Mathematical calculations are performed to demonstrate how dynamometer type wattmeters may have their measuring ranges extended
• 3.3Construction, operating principles and functions of electrical meters are outlined
• 3.4Principal methods and instruments used in resistance measurement are detailed
• 3.5Resistance measurements are conducted and verified using appropriate electrical instrumentation

4 Analyse operating principles of DC generators

• 4.1Electromotive force (EMF) equation is applied to solve problems related to DC generators
• 4.2Losses that may occur in DC generators are analysed
• 4.3Appropriate parametric relationships for DC. generator losses, together with expressions for output power and efficiency, are derived and associated numerical problems are solved
• 4.4Basic principles of DC armature winding techniques are explained
• 4.5Generator armature reaction is explained
• 4.6Expression for armature EMF is derived and applied to solve problems related to DC generators
• 4.7Commutator arcing and how this might be minimised or eliminated is explained
• 4.8Open circuit and load characteristic curves for separately excited, shunt and compound wound DC generators are derived
• 4.9Faraday’s and Lenz’s Laws are applied to solve problems relating to the electromagnetic induction of EMF and current
• 4.10Generation of EMF is illustrated by a simple, single loop conductor rotating in a uniformed magnetic field and how this EMF may be tapped to an external circuit as either AC or DC is explained

5 Analyse operating principles of DC motors

• 5.1DC torque equation is applied to solve problems related to DC motors
• 5.2Losses that may occur in DC motors are analysed
• 5.3Appropriate parametric relationships for DC motor losses, together with expressions for output power and efficiency. are derived and associated numerical problems are solved
• 5.4Speed equation for a DC motor is derived and corresponding characteristics for different winding configurations are sketched
• 5.5Speed equation and characteristics of different DC motor configurations are applied to explain how DC motor speed may be controlled
• 5.6Reasons for armature reaction and methods of compensating for its effects are identified
• 5.7Reasons why DC motors need variable starting resistors are explained
• 5.8Schematic circuits are prepared for separately excited, series, shunt and compound connected generators and motors to illustrate wiring arrangements used with DC machines

6 Compare operation of synchronous motors and generators

• 6.1Marine applications of synchronous motors and generators are identified
• 6.2Mathematical expression for the magnitude and rotational speed of the magnetic field produced by a three phase supply is derived
• 6.3Operating principles of synchronous motors are explained
• 6.4Operation of synchronous motors and generators are compared and contrasted
• 6.5Problems using phasor diagrams and mathematical expressions involving the effects of loads and excitation on synchronous motors are solved
• 6.6Advantages and disadvantages of AC synchronous motors and generators are analysed
• 6.7How alternating electrical quantities may be represented by rotating phasors is illustrated and explained
• 6.8Relationships between instantaneous, maximum, average and root mean square (RMS) values of sinusoidally alternating electrical quantities is derived
• 6.9Mathematical problems are solved by applying relationships between instantaneous, maximum, average and RMS values of sinusoidally alternating electrical quantities
• 6.10Construction features of the AC induction motor are explained
• 6.11Expression for slip of an induction motor rotor is derived and applied to frequency of its rotor EMF and current
• 6.12Expression for magnitude of rotor EMF and current is derived, taking into account distribution and pitch factors
• 6.13Relationships between rotor torque, rotor losses and slip indicating factors that affect torque are outlined
• 6.14Significance of torque/slip curves for an induction motor is explained
• 6.15Relationship between starting torque and applied voltage is established and consequences of this upon starting methods are outlined

7 Analyse operation of single and three phase transformers

• 7.1Basic transformation ratio and EMF equation for an ideal transformer is derived
• 7.2No load and on load phasor diagrams for an ideal transformer are constructed, with negligible voltage drop through its windings
• 7.3Causes of actual transformer losses are explained and relationships associated with the transformer equivalent circuit are derived
• 7.4Open circuit and short circuit tests are applied to calculate transformer efficiency and voltage regulation
• 7.5Problems related to the operation of autotransformers are solved

8 Analyse requirements for parallel operation of AC and DC generators

• 8.1Conditions required for shunt, series and compound wound DC generators to operate in parallel are identified
• 8.2Numerical problems related to parallel operation of shunt, series and compound wound DC generators are solved
• 8.3Conditions required for AC generators to operate in parallel are identified
• 8.4Numerical problems related to parallel operation of AC generators are solved
• 8.5EMF equation for an AC generator is derived, taking into account distribution and pitch factors
• 8.6Voltage regulation for synchronous generator is defined
• 8.7Effect of power factor on load characteristic of an AC generator is illustrated

9 Explain how principles of electrolytic action apply to electrical cells and batteries

• 9.1Kirchhoff’s circuit laws are explained
• 9.2Calculations to solve problems involving currents, voltage drop and terminal potential difference for cells connected to form batteries in series and in parallel are performed
• 9.3Calculations to solve secondary cell charging and discharging problems are performed
• 9.4Calculations to solve problems related to the efficiency of cells are performed

10 Analyse a magnetic circuit

• 10.1Key parameters of magnetic circuits are identified
• 10.2Formula for calculating the amount of flux generated by a multi-turn solenoid coil carrying a current to give the B/H relationship is applied
• 10.3Significance 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
• 10.4How a magnetic circuit may be created by using a toroidal core within the solenoid coil is demonstrated
• 10.5Calculations to solve problems relating to magnetic circuits using different materials in different parts of their cores, including air gaps, are performed
• 10.6Effect on flux density of applying an alternating magnetising force to an iron core is shown diagrammatically

11 Analyse operation of polyphase AC circuits

• 11.1How three phase AC may be developed out of simple single phase AC is explained
• 11.2Voltage and current relationships between line and phase in both Star and Delta three phase connections are derived
• 11.3Standard Star-to-Delta and Delta-to-Star conversion relationships for current and voltage are derived
• 11.4Numeric problems involving both balanced and unbalanced circuit loads are solved
• 11.5Relationships between kilowatt (kW), kilovolt-ampere (kVA) and kilovolt-ampere reactive (kVAr) for three phase AC circuits are derived
• 11.6Calculations are performed using the relationship between kW, kVA and kVAr to solve problems in three phase AC circuits

12 Analyse circuits that incorporate combinations of resistive, inductive and capacitive elements

• 12.1Time constant for different circuit combinations subjected to DC EMFs is defined
• 12.2Calculations 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
• 12.3Differentiation is made between inductive reactance, capacitive reactance and impedance as applied to AC circuits
• 12.4Effects of inductive and capacitive reactance upon phasor relationships between applied AC voltage and current are shown
• 12.5Concept 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
• 12.6Power factor is defined and concepts of real and reactive power usage are applied to solution of problems involving RL and RC elements

13 Describe basic operating principles of shipboard DC machinery

• 13.1EMF equation for a DC generator to solve shipboard problems is applied
• 13.2Torque equation for a DC motor to solve shipboard problems is applied
• 13.3Expression linking back EMF parameters for a DC motor is derived and used to solve shipboard problems
• 13.4Various losses that can occur in DC motors and generators are calculated

14 Explain operating principles of basic electrical instrumentation

• 14.1Schematic circuit diagrams are prepared that illustrate the main features and applications of moving coil and moving iron voltmeters and ammeters
• 14.2Schematic circuit diagrams are prepared that illustrate the main features and applications of air and iron cored dynamometer type wattmeters
• 14.3Dangers associated with current and voltage transformers on high current and voltage systems are identified

What does an assessment tool for MARL038 need to cover?

To satisfy the Principles of Assessment and Rules of Evidence, an assessment for MARL038 needs to address all 181 unit components: 14 elements with 93 performance criteria, 8 performance evidence requirements, 79 knowledge evidence requirements, and the foundation skills. A coverage matrix mapping each question and task to these components is what an auditor looks for.

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