Unit of competency: UEENEEG102A - Solve problems in low voltage a.c. circuits

 

Retrieved from: https://training.gov.au/Training/Details/UEENEEG102A 12/02/2020

 

Unit Descriptor

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.

Application of the Unit

Not Applicable

 

Licensing/Regulatory Information

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.

 

Pre-Requisites

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 Information

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

 

Elements and Performance Criteria Pre-Content

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.

 

Elements and Performance Criteria

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

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

Software/Hardware Used

Software
Hardware