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SP0504 Power Transformer Testing POWER TRANSFORMER TESTING SWP • Hold current licences for any vehicles and equipment they 1. PURPOSE AND SCOPE may be required to operate. The purpose of this Standard Work Practice (SWP) is to Required Training standardise and prescribe the method for testing power transformers. Staff must be current in all Statutory Training relevant for the task. Testing of current transformers, voltage transformers or auxiliary transformers internal to the power transformer are not included in All workers must have completed Field Induction or have this SWP. recognition of prior Ergon Energy Field Experience. Contractors must have completed Ergon Energy's Generic 2. STAFFING RESOURCES Contractor Worker Induction. Adequate staffing resources with the competencies to safely complete the required tasks as per MN000301R165: 8 Level Field 3. DOCUMENTATION Test Competency CS000501F115 . Daily/Task Risk Management Plan These competencies can be gained from, but not limited to any or ES000901R102 . Health and Safety Risk Control Guide all of the following:- SP0504R01. Power Transformer Testing Job Safety Analysis • Qualifying as an Electrical Fitter Mechanic. SP0504C01R01. Power Transformer IR and DDF Temperature • Qualifying as a Technical Service Person. Correction • Training in the safe use of relevant test equipment. SP0504C04. Power Transformer No Load Loss Test Report Requirement for all live work: SP0504C05. Power Transformer Load Loss Test Report • Safety Observer (required for all “live work” as defined in SP0504C06. Power Transformer Load Loss and Impedance the ESO Code of Practice for Electrical Work). Calculation All resources are required to: SP0504C08. Power Transformer Testing Competency Assessment • Have appropriate Switching and Access authorisations for the roles they are required to perform and have the ability SP0504C13. Construction Tool – Power Transformer to assess and maintain relevant exclusion zones from SP0504C12. Commissioning Tool – Power Transformer exposed live electrical apparatus. SP0506. Substation Primary Plant and Secondary Systems Field Testing SWP Check this is the latest Process Zone version before use. Page 1 of 14 Standard Work Practice SP0504 Ver 4 Ergon Energy Corporation Limited ABN 50 087 646 062 Ergon Energy Queensland Pty Ltd ABN 11 121 177 802 POWER TRANSFORMER TESTING SWP SM0701. Power Transformer Oil Sampling Additional test equipment: Shorting leads, Multimeters, Surface thermometer, Oil sample test equipment and Oil Spill kit. SM0701R01. Power Transformer Oil Sampling Job Safety Analysis Load Loss test equipment: Supply source capable of supplying at least 50% of winding Full Load Current (FLC), RMS Voltmeter, SM0701R02. Maintenance Instruction for Power Transformer Oil Measuring VTs, Ammeter, Metering CTs, Wattmeter, (These Sampling meters may be replaced by power analysers or other appropriate STNW1162. Standard for Managing Insulating Oil Sampling, meters) and shorting bars capable of full rated current of the Testing and Actioning the Results winding to be shorted. STNW1160. Standard for Maintenance Acceptance Criteria No Load Loss test equipment: Voltage source capable of rated MN000301R172. Doble DLA Testing voltage of transformer under test, average and RMS Voltmeters and measuring VTs, Ammeters, Metering CTs, Wattmeter, DIRANA User Manual (These meters may be replaced by power analysers or other Doble 5200 User Guide appropriate meters). MPD 600 Test Procedure Power Frequency Withstand test equipment: Suitable single- phase test transformers of sufficient voltage and VA, voltage and P53. Operate the Network Enterprise Process current measuring equipment, ammeter with parallel spark gap AS 2374.1 Power Transformers and measurement VT and voltage meter. AS 2374.3.0 Power Transformers – Insulation levels and Over-potential Withstand tests equipment: A three phase high dielectric tests – General requirements frequency generator, three phase interposing test transformer, voltage and current measuring equipment suitable for use at the Test Equipment Manuals test frequency: Transformer Manual / Manufacturer’s Drawings Voltage meters to measure test voltage (with input impedance to J and P Transformer Book match voltage divider). Ammeters to measure the phase current. 4. KEY TOOLS AND EQUIPMENT Safety Barriers and warning signs. Test Equipment within calibration date, tested and tagged: HVIA Operating Equipment: PEDs, Live Line Tester, Class 0 Insulation Resistance tester, High Voltage test set, Digital gloves. All equipment to be inspected and confirmed within test Voltmeter, Ratiometer or Primary Injection Voltage source, Phase date prior to use. Angle meter and Ohmmeter. Check this is the latest Process Zone version before use. Page 2 of 14 Standard Work Practice SP0504 Ver 4 Ergon Energy Corporation Limited ABN 50 087 646 062 Ergon Energy Queensland Pty Ltd ABN 11 121 177 802 POWER TRANSFORMER TESTING SWP Standard PPE: Full-length high visibility protective cotton clothing, As described in Substation Primary Plant and Secondary safety footwear and helmet. Systems Field Testing SWP SP0506 particular safety risks applicable to bus assemblies include: Additional PPE as required: Leather work gloves, class 00 gloves, hearing protection, safety eyewear. All PPE to be inspected and • Contact with high voltage at the transformer primary confirmed within test date (where applicable) prior to use. connections. Sun protection to be used when working outdoors. • High fault current at the transformer primary connections. • Unearthed CT and VT secondary winding. 5. WORK PRACTICE STEPS • Open circuit CT secondary terminals. 5.1. Carry out an On Site Risk Assessment • Open DLA test terminal on transformer bushing. Prior to performing this activity any hazards associated with prerequisite tasks at the worksite shall be identified and assessed • Stored energy in the transformer magnetic field (refer to with appropriate control measures implemented and documented winding resistance testing). in accordance with the Daily / Task Workplace Risk • Induced voltages and currents from nearby energised / Management Plan (CS000501F115 ) and using the Health and loaded plant. Safety Risk Control Guide reference document (ES000901R102 ). • Working at height hazards. If any risks cannot be managed or reduced to an acceptable 5.3. Assessment Criteria level, do not proceed with the task and seek assistance from your Unless stated, refer to STNW1160 Standard for Maintenance Supervisor. Acceptance Criteria for minimum acceptance values for each 5.2. All Work To Be Done With Power Transformer test. De-Energised 5.4. Record Identification Details All of the tests described in this SWP should be carried out with Record identification details: the transformer de-energised and appropriate control measures in place (e.g. barriers, matting) to prevent inadvertent contact with • Manufacturer's name and manufacturer's serial number. adjacent live plant or breaching exclusion zones. Furthermore, • Plant/Asset number. the P53 Operate the Network Process is applicable at all times for isolation and earthing. • Power ratings. Issue a Test Permit and follow the requirements of P53 Operate • Cooling configurations, e.g. ONAN, ODAF. the Network Process. • Number of windings. Check this is the latest Process Zone version before use. Page 3 of 14 Standard Work Practice SP0504 Ver 4 Ergon Energy Corporation Limited ABN 50 087 646 062 Ergon Energy Queensland Pty Ltd ABN 11 121 177 802 POWER TRANSFORMER TESTING SWP • Rated voltage. A common mistake when testing transformers is to have test • results influenced by external equipment such as surge diverters Vector group. or internal equipment such as VTs or auxiliary transformers. • Tap-changer range and tap size. Plan test connections so that clearances are greater than 5.5. Visual Inspection of Power Transformer Condition minimum withstand: Inspect the transformer for any sign of damage or leaks. Confirm • Between high voltage test leads. oil level is correct before testing commences, assembly is • Between high voltage test leads and equipment under complete and no transport bracing has been left in place. test, other apparatus or earth. Inspect the external surfaces and ensure the transformer is clean 5.7. Carry out Auxiliary and Control Circuit Voltage and dry. Withstand. Check all connections for adequate labelling. The connections The power transformer auxiliary and control circuitry shall be should be unambiguous, legibly and adequately marked. subjected to a 1 minute power frequency withstand test at 2kV to 5.6. Preliminary Steps confirm insulation integrity. Identify transformer to be tested. a) If the transformer is new and HV testing has been verified as satisfactorily completed at the manufacturer’s works – In a substation: No HV withstand test. • Ensure the transformer windings to be tested are de- b) If the transformer is new and HV testing has not been energised, tested and proved dead and earthed. verified as satisfactorily completed at the manufacturer’s • Erect Safety barriers and warning signs and issue Test works – HV withstand test. Permit if applicable. c) If the transformer is aged or refurbished and minimal In a workshop: wiring changes have occurred – No HV withstand test. • Testing should be within designated test bays or d) If the transformer is aged or refurbished and the wiring barricaded and warning signed test areas. has been substantially modified – HV withstand test. Disconnect the transformer windings from overhead bus, pothead The circuitry shall be considered
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