23897 Demonstrate knowledge of power transformer theory for (DOC) by pptfiles


									23897 version 1 Page 1 of 3

Demonstrate knowledge of power transformer theory for electricity supply
Level Credits Purpose 2 3 This unit standard covers introductory knowledge to single-phase and threephase 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. Subfield Domain Status Status date Date version published Planned review date Entry information Accreditation Standard setting body (SSB) Electricity Supply Electricity Supply - Core Skills Registered 25 October 2007 25 October 2007 31 December 2012 Open. Evaluation of documentation by NZQA. Electricity Supply Industry Training Organisation 0120

Accreditation and Moderation Action Plan (AMAP) reference

This AMAP can be accessed at http://www.nzqa.govt.nz/framework/search/index.do. Special notes 1 2 This unit standard has been developed for assessment off-job. Performance and work practices in relation to the elements and performance criteria 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 Safety Manual – Electricity Industry (SM-EI) (2004) 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.

 New Zealand Qualifications Authority 2010

23897 version 1 Page 2 of 3 3 ‘Industry requirements’ include all industry and workplace documented policies, procedures, specifications, business and quality management relevant to the workplace where assessment is carried out. For assessment purposes candidates will be supplied with appropriate formulae and the use of calculators will be permitted. This unit standard is intended for use in the assessment of Line Mechanics and all terminology and practice should be related to that sector of the industry. Useful texts include: The Lines Mechanic Handbook 5th Edition 2004; Electrical Engineers Association of New Zealand (Inc). Electrotechnology Principles and Practice 2nd Edition 2004; The Open Polytechnic of New Zealand.




Elements and performance criteria
Element 1 Demonstrate knowledge of the principles of transformers. Range single phase, three phase, instrument.

Performance criteria 1.1 Construction of a transformer is drawn, the parts are identified and their function described. Range iron core, primary and secondary windings, tapping and tapping switches, oil filled, tanks, bushings, mountings.


Principle of operation is explained through use of diagrams. Range magnetic fields, mutual induction.


Transformation ratios are described and expressed as a formula.

Element 2 Demonstrate knowledge of transformer connections and configuration. Range single and three phase transformers; star connections, delta connections, delta/star configurations, paralleling and single wire earth return (SWER).

Performance criteria 2.1 Connections and configurations are drawn and fully labelled. Range voltages, phase to phase, phase to neutral, and phase to earth are shown.

 New Zealand Qualifications Authority 2010

23897 version 1 Page 3 of 3 2.2 The purpose of earthing connections is described in accordance with current performance and work practices.

Please note Providers must be 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. Industry Training Organisations must be accredited by NZQA before they can register credits from assessment against unit standards. Accredited providers and Industry Training Organisations assessing against unit standards must engage with the moderation system that applies to those standards. Accreditation 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.

 New Zealand Qualifications Authority 2010

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