NZQA registered unit standard
Title Demonstrate knowledge of electricity supply systems
12390 version 5
Page 1 of 8
Level
Purpose
3 Credits 5
People credited with this unit standard are able to demonstrate knowledge of: the principles of electricity; measurement of electrical quantities; electricity generation; transmission, distribution and reticulation; and switching stations, substations and associated equipment.
Classification Electricity Supply > Electricity Supply - Core Skills
Available grade Achieved
Explanatory notes
1 This unit standard is intended for, but not restricted to, off-job assessment.
2 Performance and work practices in relation to the outcomes and evidence requirements must comply with all current legislation, especially the Electricity Act
1992, and any regulations and codes of practice recognised under that statute; the
Health and Safety in Employment Act 1992; and the Resource Management Act
1991. Electricity supply industry codes of practice and documented industry procedures include the current version of the Safety Manual – Electricity Industry
(SM-EI) ( Wellington: Electricity Engineers’ Association). A full list of current legislation and industry codes is available from the Electricity Supply Industry
Training Organisation, PO Box 1245, Hamilton 3240.
3 This unit standard includes the ability to recognise where particular items of electricity supply plant and equipment can be expected to be in the overall supply system.
4 This unit standard excludes the detailed knowledge of electricity supply plant and equipment items.
5 The following terms and abbreviations relate to this unit standard:
SCADA
–
Supervisory Control and Data Acquisition system used for control, indication, and monitoring purposes.
Electricity Supply Industry Training Organisation
SSB Code 101813

New Zealand Qualifications Authority 2020

NZQA registered unit standard 12390 version 5
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Outcome 1
Demonstrate knowledge of the principles of electricity.
Evidence requirements
1.1 The physical nature of current is explained.
Range flow of electrons, conductor.
1.2 The requirements for a flow of current are defined.
Range potential difference, conductor.
1.3 Conductors, semi-conductors, and insulators are defined.
Range conductor, semi-conductor and insulator chemistry.
1.4 Electromotive force, circuit and load are defined and relationship among electromotive force, current and resistance is explained.
Range electromotive force source (for example battery), continuous circuit, resistive load.
1.5 DC and AC electromotive forces and current are defined.
Range wave forms
– unidirectional, pulsating, periodic, sinusoidal.
1.6 The concept of frequency is explained.
Range cycles per unit of time.
1.7 The concepts of capacitance, inductance, reactance and impedance are explained.
Range capacitive reactance, inductive reactance, capacitors, inductors, resistance and reactance combinations.
1.8 The concepts of leading and lagging currents are explained.
Range leading and lagging current wave forms with respect to electromotive force waveform.
1.9 The concepts of work, energy, heat, electrical energy, their equivalence and transformation are explained.
Range force x distance, potential energy, kinetic energy, mass x temperature rise x specific heat, current x electromotive force, current x resistance2
, Joule’s equivalent.
Electricity Supply Industry Training Organisation
SSB Code 101813

New Zealand Qualifications Authority 2020

NZQA registered unit standard 12390 version 5
Page 3 of 8
1.10 Mechanical, heating and electric power are explained.
Range rate of doing work, rate of heating, rate of generating or consuming electrical energy.
1.11 The concepts of reactive and apparent power and energy are explained.
Range vectors 90 degrees out of phase, vector addition.
1.12 The concept of power factor is explained.
Range ratio of real energy to apparent power, cosine of leading or lagging current angle.
Outcome 2
Demonstrate knowledge of the measurement of electrical quantities.
Evidence requirements
2.1 Multipliers up to one million and down to one millionth in the international system of units are defined.
Range kilo, mega, milli, micro.
2.2 Units for measurement of potential difference, electromotive force, current, resistance, capacitance, inductance, capacitive reactance, inductive reactance, and impedance are defined.
Range volt, ampere, ohm, farad, henry.
2.3 Units for measurement of energy, power, electrical energy (electricity) and electric power (active and reactive) are defined.
Range joule = watt-second, calorie, kilowatt-hour, watt, kilowatt, reactive volt-ampere, volt-ampere.
Outcome 3
Demonstrate knowledge of the principles of electricity generation.
Range conservation of energy, magnetic field and current relationships.
Evidence requirements
3.1 The effect of current carrying conductor is explained.
Range magnetic field present around conductor.
3.2 The effect of passing current through conductor in magnetic field is explained.
Range force moves conductor across field flux lines.
Electricity Supply Industry Training Organisation
SSB Code 101813

New Zealand Qualifications Authority 2020

NZQA registered unit standard
3.3
12390 version 5
Page 4 of 8
The effect on conductor forced through magnetic field is explained.
3.4
Range current induced in conductor.
Electromagnetic field is explained.
Range magnetic field effect of conductor coil.
3.5 Simple AC generation by field rotation is explained.
Range rotating field, electromagnetic force induced in stator winding.
3.6 Commutation and DC generation are explained.
Range static field, electromagnetic force induced in rotating winding, commutator and brushes to provide unidirectional output.
3.7 The effect on the generated electromotive force of varying the current in the electromagnetic field coils in a generator is outlined.
Range field flux increased, induced voltage increased.
3.8 The effects of balance and imbalance between generator power output and load power consumption are explained.
3.9
Range rotational speed constant, increases or decreases.
The concept of an infinite busbar is explained.
Range constant system frequency and voltage.
3.10 The effects of varying the magnetic field and generated power with generator connected to infinite busbar are explained.
Range current leads or lags system voltage, generator accepts greater or lesser load.
3.11 The concepts of single phase and three phase generation are explained.
Range single set of waveforms, three sets of waveforms, 120º displacement.
Electricity Supply Industry Training Organisation
SSB Code 101813

New Zealand Qualifications Authority 2020

NZQA registered unit standard 12390 version 5
Page 5 of 8
Outcome 4
Demonstrate knowledge of the principles of electricity transmission, distribution and reticulation.
Evidence requirements
4.1 The concept of conductor current carrying capacity is explained.
Range conductor cross-sectional area, current density, conductor resistance, heating, heat flow balance.
4.2 The basic construction of a transformer is described.
Range core of magnetic material, insulated conductor windings, terminals, main tank, insulating oil, conservator tank, means of cooling, dry type transformers, Bucholz relays.
4.3 The effects of turns ratio in transformer on output electromotive force for given input are outlined.
Range primary turns, secondary turns, winding taps, tapchanger.
4.4 The concept of ampere/turns balance in transformers is explained.
Range magnetising current, primary and secondary ampere/turns.
4.5 The purpose of transformers in electricity carriage to point of use is explained.
Range step-up and step-down secondary electromotive force.
4.6 The concept of referencing systems to the general mass of earth is explained.
Range safety, insulation levels, protection.
4.7 The requirement for insulation of conductors in electrical systems is explained.
Range safety, segregation of conductors of differing phases, insulation coordination.
4.8 The relationship of line voltage to phase voltage to earth is defined.
Range delta, star phasors,

3 factor.
4.9 Common transmission line voltages used in New Zealand are defined.
Range 220 kV, 110 kV, 66 kV, 50 kV.
Electricity Supply Industry Training Organisation
SSB Code 101813

New Zealand Qualifications Authority 2020

NZQA registered unit standard
4.10
12390 version 5
Page 6 of 8
Common sub-transmission, distribution and reticulation line voltages used in
New Zealand are defined.
Range 66 kV, 50 kV, 33 kV, 22 kV, 11 kV, 400 V.
4.11 The basic principles of high voltage direct current transmission are outlined.
Range two wire with earth return, insulation levels, converter stations, rectifiers, inverters, gains over AC transmission, AC and DC transmission costs breakeven point.
4.12 Common overhead power line and power cable configurations are described.
Range single phase and three phase conductors, bundle conductors, insulators, towers, poles, cross-arms, earthing conductors, laid-up conductors, sheaths, armouring, serving.
Outcome 5
Demonstrate knowledge of switching stations, substations and associated equipment.
Range switchyards, transmission, sub-transmission and distribution substations, transformers, switchgear, surge diverters, protective equipment, voltage and current transformers, load control equipment, communications, line traps,
SCADA equipment.
Evidence requirements
5.1 The concepts of system reliability and security are outlined and overhead line and cable differences in respect to these are explained.
Range ability to continue non-interrupted supply of electricity, ability to restore supply after interruption, time for repair.
5.2 The concepts of faults and fault current are explained.
Range insulator or insulation failure, lightning, trees, line or cable damage, impedance change, fault current determination.
5.3 The concepts of overcurrents and earth fault currents are explained.
Range phase to phase faults, phase to earth faults, typical values.
5.4 The detection of fault currents and principles of overcurrent and earth fault protective relays are described.
Range current transformers, protective relays, definite time, inverse time.
5.5 The concept of fault current breaking is outlined.
Range current zero arc extinction, restrike, fuse-links, fault level ratings.
Electricity Supply Industry Training Organisation
SSB Code 101813

New Zealand Qualifications Authority 2020

NZQA registered unit standard 12390 version 5
Page 7 of 8
5.6 The use of disconnectors and earth switches are explained.
Range isolation and earthing of conductors and plant.
5.7 Common switching station and circuit layouts are described.
Range single and double busbar, duplicate feeders, ring feeders.
5.8 Standard sub-transmission and distribution substation configurations are described.
Range high voltage switchgear, transformer(s), low voltage switchgear, protection equipment, local transformer.
5.9 Standard means of remote switching controllable loads within distribution systems are described.
Range pilot wire, mains ripple frequency injection.
5.10 Standard means of remote control of switching stations and substations are described.
Range
Planned review date
SCADA, telecommunications.
31 December 2015
Status information and last date for assessment for superseded versions
Process Version Date Last Date for Assessment
Registration
Review
1
2
26 August 1997
30 November 2000
31 December 2013
31 December 2013
Revision
Rollover and
Revision
3
4
11 February 2004
26 November 2007
31 December 2013
31 December 2013
Review 5 9 December 2010 N/A
Accreditation and Moderation Action Plan (AMAP) reference 0120
This AMAP can be accessed at http://www.nzqa.govt.nz/framework/search/index.do
.
Please note
Providers must be granted consent to assess against standards (accredited) by NZQA, or an inter-institutional body with delegated authority for quality assurance, before they can report credits from assessment against unit standards or deliver courses of study leading to that assessment.
Electricity Supply Industry Training Organisation
SSB Code 101813

New Zealand Qualifications Authority 2020

NZQA registered unit standard 12390 version 5
Page 8 of 8
Industry Training Organisations must be granted consent to assess against standards by
NZQA before they can register credits from assessment against unit standards.
Providers and Industry Training Organisations, which have been granted consent and which are assessing against unit standards must engage with the moderation system that applies to those standards.
Consent requirements and an outline of the moderation system that applies to this standard are outlined in the Accreditation and Moderation Action Plan (AMAP). The
AMAP also includes useful information about special requirements for organisations wishing to develop education and training programmes, such as minimum qualifications for tutors and assessors, and special resource requirements.
Comments on this unit standard
Please contact the Electricity Supply Industry Training Organisation info@esito.org.nz
if you wish to suggest changes to the content of this unit standard.
Electricity Supply Industry Training Organisation
SSB Code 101813

New Zealand Qualifications Authority 2020