NZQA registered unit standard
23897 version 2
Page 1 of 4
Title
Demonstrate knowledge of power transformer theory for electricity
supply
Level
3
Purpose
Credits
3
This unit standard covers knowledge to single- phase and
three-phase power transformer theory as used in the electricity
supply industry.
People credited with this unit standard are able to demonstrate
knowledge of: the principles of transformers; and transformer
connections and configuration.
Classification
Electricity Supply > Electricity Supply - Core Skills
Available grade
Achieved
Explanatory notes
1
This unit standard is intended for assessment off-job. The range statements across
the unit standard can be applied according to industry specific equipment,
procedures, and processes.
2
Safety of personnel and plant must be a priority throughout the assessment. If the
safety requirements are not met the assessment must stop and the candidate will be
assessed as not yet competent.
3
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 subsequent amendments, and any regulations, codes of practice
recognised under that statute, Health and Safety in Employment Act 1992, the
Resource Management Act 1991, and their subsequent amendments, electricity
supply industry codes of practice and documented enterprise procedures. These
include, Safety Manual – Electricity Industry (SM-EI) (2004) Wellington: Electricity
Engineers’ Association.
A full list of current legislation and industry codes is available from:
Infrastructure Industry Training Organisation
PO Box 1245
HAMILTON.
4
The phrase in accordance with industry requirements is implicit in all outcomes and
evidence requirements in this unit standard.
Infrastructure Industry Training Organisation
SSB Code 101813
 New Zealand Qualifications Authority 2016
NZQA registered unit standard
23897 version 2
Page 2 of 4
5
Definitions
Industry requirements include all asset owner requirements; manufacturers’
specifications; and enterprise requirements which cover the documented workplace
policies, procedures, specifications, business, and quality management requirements
relevant to the workplace in which assessment is carried out.
Asset owner refers to the owner of an electricity supply network that takes its point of
supply from Transpower NZ, and delivers electricity to industrial, commercial and
residential customers.
Asset owner standards are the approved documented work site methods for carrying
out work on an electrical supply network to the standard required by the asset owner.
6
This unit standard is intended for use in the assessment of Line Mechanics, Cable
Jointers and all terminology should be related to that sector of the industry.
7
Simulated electrical workplace installation is recommended, but not limited to, in
order to meet the demonstration outcome of this unit standard.
Outcomes and evidence requirements
Outcome 1
Demonstrate knowledge of the principles of transformers.
Range
single-phase, three-phase.
Evidence requirements
1.1
Construction of a transformer is drawn, the parts are identified and their function
is described.
Range
1.2
Principle of operation is explained through use of diagrams.
Range
1.3
iron core, primary and secondary windings, tapping and tapping
switches, oil filled, tanks, bushings, mountings.
magnetic fields, mutual induction.
Transformation ratios are described and expressed as a formula in simple
calculations.
Outcome 2
Demonstrate knowledge of transformer connections and configuration.
Range
single- and three-phase transformers;
star connections, delta connections, combination delta-star configurations,
paralleling and single wire earth return (SWER).
Evidence requirements
2.1
Connections and configurations are drawn and fully labelled.
Infrastructure Industry Training Organisation
SSB Code 101813
 New Zealand Qualifications Authority 2016
NZQA registered unit standard
Range
2.2
23897 version 2
Page 3 of 4
voltages, phase to phase, phase to neutral, and phase to earth are
shown.
The purpose of earthing connections is described in accordance with current
performance and work practices.
Outcome 3
Demonstrate knowledge of carrying out phasing tests on electricity power transformers.
Range
low voltage (LV), High voltage (HV) transformers.
Evidence requirements
3.1
Phasing terms are described.
includes but is not limited to – vector groupings for transformers,
phase markings and identification of conductors (R, W, B, A, B, C);
evidence of two is required.
Range
3.2
Purpose of phasing checks is described.
3.3
Methods for testing of phasing of transformers in HV systems are
demonstrated.
may include but is not limited to – use of phasing phones, use of
HV phasing and voltage detection equipment;
evidence of two is required.
Range
Planned review date
31 December 2018
Status information and last date for assessment for superseded versions
Process
Version Date
Last Date for Assessment
Registration
1
25 October 2007
31 December 2016
Review
2
20 March 2014
N/A
Consent and Moderation Requirements (CMR) reference
0120
This CMR 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,
before they can report credits from assessment against unit standards or deliver courses
of study leading to that assessment.
Industry Training Organisations must be granted consent to assess against standards by
NZQA before they can register credits from assessment against unit standards.
Infrastructure Industry Training Organisation
SSB Code 101813
 New Zealand Qualifications Authority 2016
NZQA registered unit standard
23897 version 2
Page 4 of 4
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.
Requirements for consent to assess and an outline of the moderation system that applies
to this standard are outlined in the Consent and Moderation Requirements (CMR). The
CMR 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 Infrastructure Industry Training Organisation at
qualifications@infrastructureito.org.nz if you wish to suggest changes to the content of this
unit standard.
Infrastructure Industry Training Organisation
SSB Code 101813
 New Zealand Qualifications Authority 2016