Unit of competency details

Unit Descriptor 

1 )

1 .1 ) Descriptor 

This unit covers ascertaining correct operation of single and three phase a.c. circuits and solving circuit problems as they apply to servicing, fault finding, installation and compliance work functions. It encompasses safe working practices, multiphase circuit arrangements, issues related to protection, power factor and MEN systems and solutions to circuit problems derived from calculated and measured parameters.

1 .2 ) License to practice 

During Training : Competency development activities are subject to regulations directly related to licencing, occupational health and safety and where applicable contracts of training such as apprenticeships.

In the workplace : The application of the skills and knowledge described in this unit require a license to practice in the workplace where work is carried out on electrical equipment or installations which are designed to operate at voltages greater than 50 V a.c. or 120 V d.c.

Other conditions may apply under State and Territory legislative and regulatory requirements.

Prerequisite Unit (s )

2 )

2 .1 ) Competencies 

Granting competency in this unit shall be made only after competency in the following unit(s) has/have been confirmed.

UEENEEE101A

Apply Occupational Health and Safety regulations, codes and practices in the workplace

UEENEEE104A

Solve problems in d.c circuits

UEENEEG101A

Solve problems in electromagnetic devices and related circuits

Employability Skills 

3 )

This unit contains Employability Skills

The required outcomes described in this unit of competency contain applicable facets of Employability Skills. The Employability Skills Summary of the qualification in which this unit of competency is packaged will assist in identifying Employability Skill requirements.

Application of the Unit 

4 )

4 .1 ) General Application 

This unit applies to all qualifications, competencies and/or Skill Sets which require an electrical licence.

4 .2 ) Importation 

RTOs wishing to import this unit into any qualification under the flexibility provisions of NQC Training Package Policy

6 ) Elements describe the essential outcomes of a unit of competency

Performance criteria describe the required performance needed to demonstrate achievement of the Element. Assessment of performance is to be consistent with the evidence guide.

ELEMENT 

PERFORMANCE CRITERIA 

1

Prepare to solve low voltage a.c. circuit problems.

1.1

OHS procedures for a given work area are identified, obtained and understood.

1.2

Established OHS risk control measures and procedures in preparation for the work are followed.

1.3

Safety hazards, which have not previously been identified, are noted and established risk control measures are implemented.

1.4

The nature of the circuit(s) problem is obtained from documentation or from work supervisor to establish the scope of work to be undertaken.

1.5

Advice is sought from the work supervisor to ensure the work is coordinated effectively with others.

1.6

Sources of materials that may be required for the work are established in accordance with established procedures.

1.7

Tools, equipment and testing devices needed to carry out the work are obtained and checked for correct operation and safety.

2

Solve low voltage a.c. circuit problems.

2.1

OHS risk control measures and procedures for carrying out the work are followed.

\

2.2

The need to test or measure live is determined in strict accordance with OHS requirements and when necessary conducted within established safety procedures.

2.3

Circuits/machines/plant are checked as being isolated where necessary in strict accordance OHS requirements and procedures.

2.4

Established methods are used to solve circuit problems from measure and calculated values as they apply to single and three-phase low voltage circuit.

2.5

Unexpected situations are dealt with safely and with the approval of an authorised person.

2.6

Problems are solved without damage to apparatus, circuits, the surrounding environment or services and using sustainable energy practices.

3

Complete work and document problem solving activities.

3.1

OHS work completion risk control measures and procedures are followed.

3.2

Work site is cleaned and made safe in accordance with established procedures.

3.3

Justification for solutions used to solve circuit problems is documented.

3.4

Work completion is documented and an appropriate person or persons notified in accordance with established procedures.

REQUIRED SKILLS AND KNOWLEDGE 

7)  This describes the essential skills and knowledge and their level, required for this unit.

Evidence shall show that knowledge has been acquired of safe working practices and Solving single and three phase low voltage circuit problems.

All knowledge and skills detailed in this unit should be contextualised to current industry practices and technologies.

KS01-EG102A Alternating current power circuits 

Evidence shall show an understanding of alternating currents power circuits to an extent indicated by the following aspects:

T1 Alternating Current Quantities encompassing:

• sine, cosine and tangent ratios of a right angle triangle
• Pythagoras Theorem to a right angle triangle.
• use of the CRO to measure d.c. and a.c. voltage levels
• sinusoidal voltage generated by a single turn coil rotated in a uniform magnetic fields
• terms 'period', 'maximum value', 'peak-to-peak value', 'instantaneous value', 'average value', 'root-mean-square (r.m.s.) value', in relation to a sinusoidal waveform.
• calculation of the instantaneous value of induced voltage of a generated sinusoidal waveform.
• measurement of instantaneous, peak, peak-to-peak values and the period of a sinusoidal waveform.
• calculation of root-mean-square (r.m.s.) value and frequency of a sinusoidal waveform from values of peak voltage and period.

T2 Phasors Diagrams encompassing:

• purpose of phasor diagrams
• 'in-phase', 'out-of-phase', 'phase angle'' lead' and 'lag'.
• phase angle between two or more alternating quantities from a given sinusoidal waveform diagram.
• convention for representing voltage, current and the reference quantity in a phasor diagram.
• drawing phasor diagrams to show the relationship between two or more a.c. values of voltage and/or current.
• determination of phase relationship between two or more sinusoidal waveforms from a given diagram and measurements.

T3 Single Element a.c. circuits encompassing:

• setting up and connect a single-source resistive a.c. circuit and take voltage and current measurements to determine the resistance
• determining the voltage, current resistances from measure of given values of any tow of these qualities.
• relationship between voltage drops and current in resistive a.c. circuit
• applications of resistive a.c. circuits
• defining ‘inductive reactance’.
• calculation of inductive reactance for a given inductor and the relationship between inductive reactance and frequency.
• applying Ohm’s Law to determine voltage, current of inductive reactance in a purely inductive a.c. circuit given any two to these quantities.
• applications of inductive a.c circuits.
• calculation of capacitive reactance
• applying Ohm’s Law to determine voltage, current or capacitive reactance in a purely capacitive a.c circuit given any two of the quantities.
• applications of capacitive a.c circuits

T4 RC and RL Series a.c. circuits encompassing:

• impedance and impedance triangle.
• determining the impedance, current and voltages for a series RC circuit given the resistance, capacitance and supply voltage.
• drawing and labelling the impedance triangle for a series RC circuit
• drawing phasor diagrams for a series RC circuit
• AS/NZS 3000 requirements for the installation of capacitors.
• examples of capacitive components in power circuits and systems and the effect on the phase relationship between voltage and current.
• determining the impedance, current and voltages for a series RL circuit given the resistance, inductance and supply voltage.
• drawing and labelling the impedance triangle for a series RL circuit
• drawing the equivalent circuit of a practical inductor
• Draw phasor diagrams for a series RL circuit.
• examples of inductive components in power circuits and systems and describe their effect on the phase relationship between voltage and current

T5 RLC Series a.c. circuits encompassing:

• measuring component voltages in a series RLC circuit and using a phasor diagram to determine the supply voltage and phase angle between circuit voltage and circuit current.
• determining the impedance, current and voltages for a series RLC circuit given resistance, inductance, capacitance and supply voltage.
• drawing and labelling the impedance triangle for a series RLC circuit.
• calculation of total impedance for a series RLC circuit.
• calculation of voltage drop for cables using the values for reactance and a.c. resistance from AS/NZS 3008.
• comparison of current limiting characteristics of inductors and resistors.
• practical examples of RLC series circuits

T6 Parallel a.c. Circuits encompassing:

• determining the branch currents of a parallel circuit that contain RL, RC or LC in two branches.
• using a phasor diagram to determine the total circuit current and phase angle in parallel RL, RC or LC circuits.
• determining the total circuit impedance of parallel RL, RC or LC circuits.
• measuring the branch currents in a parallel RLC circuit and use a phasor diagram to determine the total current and phase angle between circuit voltage and circuit current.
• determining the branch impedances, branch currents and phase angles voltages for a parallel RLC circuit given resistance, inductance, capacitance and supply voltage.
• calculation of impedance for a parallel RLC circuit.
• practical examples of parallel circuits.

T7 Power in an a.c. circuit encompassing:

• difference between true power, apparent power and reactive power and the units in which these quantities are measured.
• drawing the power triangle to show the relationships between true power, apparent power and reactive power
• defining the term "power factor" and phase angle.
• methods used to measure single phase power, energy and demand.

T8 Power Factor Improvement encompassing:

• effects of low power factor.
• requirements for power factor improvement.
• methods used to improve low power factor of an installation.
• local supply authority and AS/NZS 3000 wiring rules requirements regarding the power factor of an installation and power factor improvement equipment.
• methods used to measure single phase power factor.
• using manufacturers catalogues to select power factor equipment for a particular installation

T9 Harmonics and Resonance Effect in a.c. Systems encompassing:

• term "harmonic" in relation to the sinusoidal waveform of an a.c. power system.
• sources in a.c. systems that produce harmonics.
• problems that may arise in a.c. circuits as a result of harmonics and how these are overcome.
• methods and test equipment used to test for harmonics
• methods used to reduce harmonics in a.c. power system
• conditions in a series a.c. circuit that produce resonance.
• dangers of series resonance circuits
• conditions in a parallel a.c. circuit that produce resonance.
• dangers of parallel resonance circuits
• AS/NZS3000 and the local supply authority requirements concerning harmonics and resonance effect in a.c. power systems.

T10 Three Phase Systems encompassing:

• features of a multiphase system.
• comparison of voltages generated by single and multiphase alternators.
• reasons for the adoption of three phases for power systems.
• how three phases is generated in a single alternator.
• Calculation of r.m.s. value of voltage generated in each phase given the maximum value.
• relationship between the phase voltages generated in a three phase alternator and the conventions for identifying each.
• term "phase sequence" (also, referred to as "phase rotation").
• determining the phase sequence of a three phase supply

T11 Three phase star-connections encompassing:

• connecting a three phase star-connection load.
• phase relationship between line and phase voltages and line and phase currents of a star-connected system.
• determining the r.m.s. value of line and phase voltage given any one of these quantities.
• determining the r.m.s. value of line and phase current given any one of these quantities.
• terms "balanced load" and "unbalanced load".
• effect of a reversed phase winding of a star connected alternator.
• example of balanced and unbalanced loads in typical power systems.

T12 Three phase four wire systems encompassing:

• purpose of the neutral conductor in a three phase four wire systems.
• determining the effects of an high impedance in the neutral conductor of a three phase four wire system supplying an unbalanced load where MEN earthing is employed.
• determining the value and phase relationship of neutral current in an unbalanced three phase four wire systems given line currents and power factors.
• AS/NZS 3000 requirements regarding neutral conductors.
• AS/NZS 3008.1.1 method for determining voltage drop in unbalanced three phase circuits

T13 Three phase delta-connections and Interconnected systems encompassing:

• connecting three phase delta loads.
• phase relationship between line and phase voltages and line and phase currents of a delta-connected system.
• determining the r.m.s. value of line and phase voltage given any one of these quantities.
• determining the r.m.s. value of line and phase current given any one of these quantities.
• limitations and uses of open delta connections
• effect of a reversed phase winding of a delta connected transformer
• example of loads in typical power systems.
• drawing the typical combinations of three phase interconnected systems using star-connections and a delta-connection.
• relationship between line and phase voltages and line and phase currents in the typical interconnected systems using star-connections and delta-connections.

T14 Energy and power requirements of a.c. systems encompassing:

• purposes for measuring power, energy, power factor and maximum demand of a.c. power systems and loads.
• difference between true power, apparent power and reactive power and the units in which these quantities are measured in a three phase system.
• drawing the power triangle to show the relationships between true power, apparent power and reactive power in a three phase system.
• methods used to measure three phase power , energy, power factor and demand.
• determining how the power factor of a three phase installation can be improved.
• using manufacturers catalogues to select measurement equipment for a particular installation

T15 Fault Loop Impedance encompassing:

• term fault loop impedance of a a.c. power system
• determining fault loop impedance using resistance and reactance values from AS/NZS 3008.1.1
• measuring fault loop impedance of typical circuits
• procedures for testing fault loop impedance

EVIDENCE GUIDE 

9 ) The evidence guide provides advice on assessment and must be read in conjunction with the Performance Criteria, Required Skills and Knowledge, the Range Statement and the Assessment Guidelines for this Training Package.

The Evidence Guide forms an integral part of this unit. It must be used in conjunction with all parts of this unit and performed in accordance with the Assessment Guidelines of this Training Package.

Overview of Assessment 

9 .1 )

Longitudinal competency development approaches to assessment, such as Profiling, require data to be reliably gathered in a form that can be consistently interpreted over time. This approach is best utilised in Apprenticeship programs and reduces assessment intervention. It is the Industry's preferred model for apprenticeships. However, where summative (or final) assessment is used it is to include the application of the competency in the normal work environment or, at a minimum, the application of the competency in a realistically simulated work environment. It is recognised that, in some circumstances, assessment in part or full can occur outside the workplace. However, it must be in accordance with industry and regulatory policy.

Methods chosen for a particular assessment will be influenced by various factors. These include the extent of the assessment, the most effective locations for the assessment activities to take place, access to physical resources, additional safety measures that may be required and the critical nature of the competencies being assessed.

The critical safety nature of working with electricity, electrical equipment, gas or any other hazardous substance/material carries risk in deeming a person competent. Sources of evidence need to be 'rich' in nature to minimise error in judgment.

Activities associated with normal every day work have a bearing on the decision as to how much and how detailed the data gathered will contribute to its 'richness'. Some skills are more critical to safety and operational requirements while the same skills may be more or less frequently practised. These points are raised for the assessors to consider when choosing an assessment method and developing assessment instruments. Sample assessment instruments are included for Assessors in the Assessment Guidelines of this Training Package.

Critical aspects of evidence required to demonstrate competency in this unit 

9 .2 )

Before the critical aspects of evidence are considered all prerequisites shall be met.

Evidence for competence in this unit shall be considered holistically. Each element and associated performance criteria shall be demonstrated on at least two occasions in accordance with the 'Assessment Guidelines - UEE07'. Evidence shall also comprise:

• A representative body of work performance demonstrated within the timeframes typically expected of the discipline, work function and industrial environment. In particular this shall incorporate evidence that shows a candidate is able to:

• Implement Occupational Health and Safety workplace procedures and practices including the use of risk control measures as specified in the performance criteria and range statement
• Apply sustainable energy principles and practices as specified in the performance criteria and range statement
• Demonstrate an understanding of the essential knowledge and associated skills as described in this unit. It may be required by some jurisdictions that RTOs provide a percentile graded result for the purpose of regulatory or licensing requirements.
• Demonstrate an appropriate level of skills enabling employment
• Conduct work observing the relevant Anti Discrimination legislation, regulations, polices and workplace procedures

• Demonstrated consistent performance across a representative range of contexts from the prescribed items below:

• Solve problems in single and three phase circuits as described as described in 8) and including:

A

Using methodological techniques to solve problems in circuits in a.c. circuits from measure and calculated values

B

Determining the operating parameters of existing circuits

C

Altering an existing circuit to comply with specified operating parameters.

D

Developing circuits to comply with a specified function and operating parameters.

E

Determining the cause of low power factor in an existing circuit.

F

Determining conditions causing an existing circuit to be unsafe.

G

Dealing with unplanned events

Context of and specific resources for assessment 

9 .3 )

This unit should be assessed as it relates to normal work practice using procedures, information and resources typical of a workplace. This should include:

• OHS policy and work procedures and instructions.
• Suitable work environment, facilities, equipment and materials to undertake actual work as prescribed by this unit.

These should be part of the formal learning/assessment environment.

Note:

Where simulation is considered a suitable strategy for assessment, conditions must be authentic and as far as possible reproduce and replicate the workplace and be consistent with the approved industry simulation policy.

The resources used for assessment should reflect current industry practices in relation to solving single and three phase low voltage circuit problems.

Method of assessment 

9 .4 )

This unit shall be assessed by methods given in Volume 1, Part 3 'Assessment Guidelines'.

Note: Competent performance with inherent safe working practices is expected in the industry to which this unit applies. This requires assessment in a structured environment which is primarily intended for learning/assessment and incorporates all necessary equipment and facilities for learners to develop and demonstrate the essential knowledge and skills described in this unit.

Concurrent assessment and relationship with other units 

9 .5 )

For optimisation of training and assessment effort, competency development in this unit may be arranged concurrently with unit:

RANGE STATEMENT 

8 ) This relates to the unit as a whole providing the range of contexts and conditions to which the performance criteria apply. It allows for different work environments and situations that will affect performance.

This unit shall be demonstrated in relation to solving problems in a.c. circuit by:

• Determining the operating parameters of existing circuits
• Altering an existing circuit to comply with specified operating parameters
• Developing circuits to comply with a specified function and operating parameters of voltage, current, impedance, power and power factor
• Determining the cause of low power factor in an existing circuit.
• Determining conditions causing an existing circuit to be unsafe includes electric shock hazard from indirect contract with conductive parts, insufficiently low impedance of a fault current path and inadequate fault protection.

In relation to the following on more than one occasions:

Single phase circuits 

• Connecting single-phase circuits
• Choosing correct instruments
• Taking measurements correctly and accurately.

Three-phase circuits 

• Connecting three-phase circuits
• Choosing correct instruments
• Taking measurements correctly and accurately.

AND

At least four of the following applications 

• Series a.c. circuits
• Parallel a.c. circuits
• Series / parallel a.c. circuits
• Single phase motors / controls
• Three phase motors / controls
• Synchronous machines
• Transformers / Auxiliary components
• Star connected circuits
• Delta connected circuits
• Star-Delta interconnected circuits
• Open Delta circuits

Generic terms used throughout this Vocational Standard shall be regarded as part of the Range Statement in which competency is demonstrated. The definition of these and other terms that apply are given in Volume 2, Part 2.1.

2 .2 ) Literacy and numeracy skills 

Participants are best equipped to achieve competency in this unit if they have reading, writing and numeracy skills indicated by the following scales. Description of each scale is given in Volume 2, Part 3 'Literacy and Numeracy'

Reading

4

Writing

4

Numeracy

4

Competency Field 

5 )

Electrical