UEEEL0077 - Evaluate and report on the performance of LV machines

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Unit code: UEEEL0077 | Study level: TAFE
Credit points
N/A
Location
Sunshine
Prerequisites
UEEEL0020 - Solve problems in low voltage a.c. circuits; and
UEEEL0021 - Solve problems in magnetic and electromagnetic devices
(Or equivalent to be determined by unit coordinator)
Overview
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Overview

This unit covers determining correct operation of single and three phase machines, evaluating and reporting on their performance.It includes safe working practices, machine connections circuit arrangements, issues related to machine operation, characteristics and protection and solutions to machine problems derived from calculated and measured parameters.

Assessment

For Melbourne campuses

Assessment tasks will be designed to reinforce & extend knowledge and skill competence within set & controlled parameters in accordance with each unit's learning outcomes & performance criteria requirements, including the setting of work based practical application tasks designed to provide evidence of competence outcomes, within periodic and scheduled timelines.

Students will be expected to demonstrate the following required skills:

  • evaluating the operating parameters of existing machines
  • recommending alterations to an existing machine for compliance with specified operating parameters
  • justifying selection of machines/circuits to comply with a specified function and operating parameters
  • determining the cause of problems in an existing machine
  • determining solutions for problems in an existing machine
  • determining conditions causing an existing machine to be unsafe
  • recommending solutions for identified machine problems
  • determining correct machine for a specified range of applications
  • determining parameters for the equivalent circuit using data from short circuit and open circuit tests
  • determining percentage resistance, reactance and impedance of a transformer
  • determining voltage regulation using percentage resistance, percentage reactance and load power factor
  • determining parameters for maximum regulation and zero regulation.

Students will also be expected to demonstrate the following knowledge:
*single and three phase transformers including:
-transformer construction including:
types of lamination style and core construction used in single-phase, three phase, double wound, auto transformers and instrument transformers
identification of different winding styles/types used in transformers
methods used to insulate low and high voltage transformers
construction of transformer tanks for distribution transformers
transformer auxiliary equipment
function of transformer auxiliary equipment
types of information stated on transformer nameplates
application of transformers
performing basic insulation resistance, continuity and winding identification tests

-transformer operation including:
principles of mutual induction of a transformer
factors that determine the induced voltage in a transformer winding
determining the value of a transformer's secondary voltage and current given one winding’s electrical details and the turns ratio
identification of voltage and current components of a phasor diagram for a transformer no-load and load
principles of power transferred from the primary to the secondary when a load is connected using a phasor diagram neglecting impedance drops
selecting transformers for specific application/s
safety features specified in AS/NZS3000 with respect to transformers and isolating transformers
transformer resistance, reactance and impedance, including total equivalent values, referred to the primary and the secondary
equivalent circuit of a transformer
harmonics in transformers, including their generation, measurement, problems they cause and overcoming their impact
purpose of tertiary windings
-transformer losses, efficiency and cooling including:
power losses which occur in a transformer
tests which allow the power losses of a transformer to be determined
determination of transformer losses and efficiency using test results
efficiency for loads other than full load
relationship between transformer cooling and rating
methods used for natural and forced cooling of transformers
properties of transformer oil
tests conducted on transformer oil
-transformer voltage regulation and percent impedance including:
voltage regulation as applicable to a transformer
reasons for voltage variation in the output of a transformer
determine the voltage regulation of a transformer from voltage and percentage impedance values
percentage impedance as applied to transformers
determine the percent impedance by using test results and percent impedance of a transformer by calculation
approximate voltage drop and exact voltage drop equations
-parallel operation of transformers and transformer auxiliary equipment including:
determine polarity markings for an unidentified single phase double wound transformer
need for parallel operation of transformers
conditions/restrictions required before two transformers can be connected in parallel
vector grouping
connecting transformers in parallel to supply a single load
loading on transformers operating in parallel
consequences/effect of an incorrect connection
-auto-transformers and instrument transformers including:
identification of auto-transformers, voltage transformers and current transformers from their winding diagrams
determining voltage and current in the windings of an auto-transformer by calculation
advantages and disadvantages of an auto-transformer
AS/NZS3000 requirements with respect to transformers
construction and ratings of voltage transformers and current transformers
precautionary measures taken to connect and disconnect instrument transformers
connection diagrams for instrument transformers
applications for auto-transformers and instrument transformers
*alternating current rotating machines including:
-operating principles of three phase induction motors including:
characteristics of the magnetic field produced by a single-phase, two-phase and three-phase windings
speed of rotation of a rotating magnetic field
relationship between the rotor speed, slip and rotor frequency
basic principle of operation of an induction motor
reversing the direction of rotation of a three-phase induction motor
-three phase induction motor construction including:
basic component parts of a three-phase induction motor
types of rotors used in three-phase induction motors
connecting a three-phase induction motor in both star and delta
testing insulation resistance of a three-phase induction motor prior to connection to the supply
testing winding resistance (ohmic value and continuity) of a three-phase induction motor prior to connection to the supply
-three phase induction motor characteristics including:
relationship between torque, speed, and power and interpretation of speed/torque curves of induction motors
squirrel cage motors operating characteristics conditions necessary for an induction motor to produce maximum torque
operating characteristics of an induction motor from name plate information and by measurement
induction motor efficiency and minimum energy performance standards (MEPS)
full load efficiency and power factor of induction motors
comparison of the advantages of squirrel cage and wound rotor induction motors
-single-phase motors – split phase including:
common types of single-phase motors
principles of operation of split phase induction motors
construction and basic characteristics of split phase induction motors
applications of split phase induction motors
operation of split phase induction motors
-single phase motors – capacitor including:
identification of single-phase induction motors including capacitor start, capacitor start/capacitor run and permanent split capacitor (PSC)
principles of operation
operating characteristics and typical applications
connection and running
reversing the direction of rotation
-single phase motors –shaded pole including:
principles of operation
operating characteristics and typical applications
connection and running
reversing the direction of rotation
-single phase motors – universal including:
principles of operation
identification and functions of each of the basic parts
operating characteristics and typical uses
connecting, running and reversing
-motor protection including:
reasons why motor protection is required
requirements of the AS/NZS3000 Wiring rules with regards to motor protection
types of motor overload protection
operating principles of microtherm devices, thermal and magnetic motor protection devices
electrical features of motor protection HRC fuses
effects of under voltage and over voltage and of repetitive starting and/or reversing on motors and motor circuits
special requirements for motor protection, in high humidity or moist environments, high temperature areas and corrosive atmospheres
operating principles of phase failure protection
selecting suitable protection devices for a given motor and starter combination
-three phase synchronous machines- operation principles and construction including:
power transfer diagram of an a.c. synchronous machine
need for the generation of a sinusoidal waveform
principles of operation of a synchronous alternator, of operation of a synchronous motor and an asynchronous generator (induction generator)
identification of main parts of a synchronous alternator/motor
methods used to provide the excitation of a synchronous alternator/motor
block diagram of an alternator voltage regulator
advantages gained by the parallel operation of alternators
starting methods of synchronous motors
vee curves
behaviour of synchronous motors at various excitation levels and their associated phasor diagrams
limits of stability for synchronous motors
-alternators and generators including:
effects on the generated voltage of variations in excitation and on generated voltage of variations in load
types of prime movers used with single and three phase portable/standby alternators
manual operation of single and three phase portable/standby alternators
ratings of single and three phase portable/standby alternators
applications of single and three phase portable/standby alternators
construction details of single and three phase portable/standby alternators
common faults found in portable/standby alternators
limits of stability for synchronous alternators.

Required reading

The qualified trainer and assessor will provide teaching and learning materials as required in the form of workbooks produced by the VU Polytechnic and/or via the Victoria University Polytechnic e-Learning system.

As part of a course

This unit is studied as part of the following course(s):

Advanced Diploma of Engineering Technology - Electrical
UEE62122 | Advanced diploma | Duration:

Refer to the course page for information on how to apply for the course. VU takes care to ensure the accuracy of this unit information, but reserves the right to change or withdraw courses offered at any time. Please check that unit information is current with the Student Contact Centre.

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