ELECTRICITY SUPPLY - POWER SYSTEM MAINTENANCE Carry out routine inspection and service on oil filled distribution power transformers 11kV to 400V

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1 1 of 8 level: 4 credit: 8 planned review date: December 2006 sub-field: purpose: entry information: Electricity Supply People credited with this unit standard are able to: prepare for routine service transformers 11kV to 400V; carry out routine inspections and prescribed diagnostic tests; carry out servicing; record routine inspection and servicing; and return equipment to service. Prerequisites: Unit 14287, Use and maintain test instruments used in high voltage electrical industry; Unit 14294, Carry out insulating oil sampling and voltage breakdown tests; Unit 14701, Manage electricity supply work control system; Unit 14700, Apply and remove safety measures in an electricity supply environment; Unit 12296, Apply earths to and remove earths from electrical conductors, plant and equipment; or demonstrate equivalent knowledge and skills. Core electrical theory is essential knowledge underpinning the performances required by this unit standard. accreditation option: moderation option: Evaluation of documentation and visit by NZQA and industry. A centrally established and directed external moderation system has been set up by the Electricity Supply Industry Training Organisation.

2 2 of 8 special notes: 1 This unit standard can be assessed in a workplace environment, or in a training or educational environment if simulated equipment response and examples are able to be provided, or in a combination of both environments. 2 Performance and work practices in relation to the elements and must comply with all current legislation, especially the Electricity Act 1992, and any regulations, codes of practice recognised under that statute, Health and Safety in Employment Act 1992, Building Act 1991, Resource Management Act 1991, and their subsequent amendments; Electricity Regulations 1997, Safety Rules Electricity Industry: Safety Rules for the New Zealand Electricity Generation, Transmission and Distribution Industry. (2000) Wellington: Electricity Engineers Association of NZ (SR-EI), and General Safety Guide Electricity Industry: Guidance on General Safety in the New Zealand Electricity Generation, Transmission and Distribution Industry. (2000) Wellington: Electricity Engineers Association of NZ (GSH-EI); Electricity Engineers Association Codes of Practice; Occupational Safety and Health Approved Codes of Practice; New Zealand Electrical Codes of Practice (NZECP). A full list of current legislation and industry codes is available from: Electricity Supply Industry Training Organisation PO Box 1245 HAMILTON.

3 3 of 8 3 Reference to terms, procedures, and specifications in this unit standard may be taken as including documented procedures and specifications relevant to the workplace in which assessment is carried out. 4 All work practices shall meet documented enterprise maintenance standards, including the quality management requirements, and the documentation of activities, events, and decisions. 5 The range of this unit standard is limited to carrying out preventative maintenance and replacement and/or repairs of distribution power transformers, 11kV to 400V, normally applied at electricity distribution substations. 6 The following terms and abbreviations relate to this unit standard. IEC = International Electrotechnical Commission. Elements and Performance Criteria element 1 Prepare for routine service. 1.1 The scope of work and equipment are identified and selected in accordance with servicing procedures. may include but is not limited to associated client or enterprise check and/or inspection lists and procedures for - power transformers, voltage regulators, reactors.

4 4 of The anticipated replacement spares are made available. may include but is not limited to the completion of the necessary documentations, where required, to uplift client held spares. 1.3 The equipment is released from operational use. may include but is not limited to the correct and timely completion of all the prescribed equipment release requests. 1.4 The defect history and plant history records are scrutinised for indications of servicing needs. may include but is not limited to - known defects, operator reports, client special service requests, oil analysis, dissolved gas analysis, thermography tests. 1.5 The required access permit, or recognised equivalent, is received, checked, and signed in accordance with the industry and enterprise requirements. may include but is not limited to a careful check of the isolations to ensure the access permit, or recognised equivalent, provides a safe work environment. 1.6 All safety measures are in place to eliminate, minimise, or control hazards in the permit area. includes inspection of the safe working zone to ensure this safe work area has been correctly delineated and provides a safe work environment. 1.7 The work party is fully briefed on the equipment to be worked on, work to be done, safe working zone and safety features in place, and have signed the access permit or its approved equivalent. All communication with the work party is clear and unambiguous. includes the ability to resolve any concerns the work party may have over the isolations and the delineation of the safe work area.

5 5 of 8 element 2 Carry out routine inspections and prescribed diagnostic tests. 2.1 People and equipment are resourced for the required work. may include but not limited to - people, tools, spares, materials, inspection sheets, procedure sheets, diagnostic test equipment. 2.2 Inspection and diagnostic tests are completed in accordance with the selected procedures. may include but not limited to applying tests in accordance with IEC 76 or quoted standards for the following items. The deviation to be less than what the client has prescribed; windings - resistance of windings, thermometer calibration, insulation resistance bushing insulation resistance; cooling system - all pump operation, alarms and settings; protection - Buchholz relay indications, pressure relief valve, thermal alarms, oil flow indication, tap change operation, oil inspection for oil leaks, take oil samples for analysis; general - check plinth footings. 2.3 All diagnostic test results are interpreted and analysed for compliance with standard. may include but not limited to results that are outside of client, manufacturer or international standards and where corrective action is required. Interpretation of results may include recommendations for servicing action.

6 6 of 8 element 3 Carry out servicing. 3.1 All required servicing is carried out consistent with guidelines and procedures. may include but not limited to the following activities - on line oil filters checked, cleaning ceramic bushings, Buchholz relay operation checks, replacement of oil pump bearings or unit, fan motor repairs, remove blockages in oil system, check seismic constraints are secure, oil treatment and re-testing, tap changer inspection and oil change. 3.2 All equipment is reinstated on the transformers. may include but not limited to - all restored equipment is fitted correctly in the proper order and secured ready for service, connections tight and electrically correct, oil levels are correct to level indication. 3.3 The on load tap change contacts are serviced. may include but is not limited to - checking, cleaning, repairing, replacing. 3.4 The on load tap change drive mechanism is serviced. may include but is not limited to - checking, cleaning, repairing, replacing.

7 7 of 8 element 4 Record routine inspection and servicing. 4.1 The as left conditions are recorded in the plant history or defect history. may include but not limited to - analysis and reporting of any defects, correct completion of the plant history, including items replaced. 4.2 The equipment condition status is recorded in accordance with client requirements. may include but not limited to - cyclo recorder, number of trial operations noted, pressures and auxiliary service quantified, replacement spares fitted. element 5 Return equipment to service. 5.1 Work party are withdrawn and warned the equipment is no longer safe to work on. includes notification to the work party to regard the equipment as live when they have signed off. 5.2 All tools and recipient applied safety measures are removed in accordance with client requirements. includes all access devices, for example, work platforms, scaffold, cherry pickers.

8 8 of All equipment worked on is inspected and set for return to service. includes - confirming all equipment and the work party are clear, all operational equipment which has been worked on is now set ready for service. 5.4 Returned of access permit, or its approved equivalent, is confirmed. includes - confirming all members of the work party have signed off, the equipment is returned to service without incident. Comments on this unit standard Please contact the Electricity Supply Industry Training Organisation ceo@esito.org.nz if you wish to suggest changes to the content of this unit standard. Please Note Providers must be accredited by the Qualifications Authority or a delegated interinstitutional body before they can register credits from assessment against unit standards or deliver courses of study leading to that assessment. Industry Training Organisations must be accredited by the Qualifications Authority 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 providers wishing to develop education and training programmes, such as minimum qualifications for tutors and assessors, and special resource requirements. This unit standard is covered by AMAP 0120 which can be accessed at