Equipment Strategy For Earthing Transformers Strategy

Transcription

1 ASM-STR-A Versin: 2.0 Equipment Strategy Fr Earthing Transfrmers Strategy Equipment Strategy Fr Earthing Transfrmers Strategy Current versin: 28/06/2018 EXTERNAL USE Page 1 f 8 Next revisin due: 28/06/2022 HARDCOPY IS UNCONTROLLED Pwerlink Queensland

2 ASM-STR-A Versin: 2.0 Equipment Strategy Fr Earthing Transfrmers Strategy Table f cntents 1. Intrductin Purpse Scpe References Defined terms Mnitring and cmpliance Risk management Strategy Prjected use f equipment Design philsphy Design requirements Service envirnment Operating cntext Technlgies traditinally used by Pwerlink Technlgies available nw Equipment strategy elements Cncurrent investigatins: Summary... 8 Current versin: 28/06/2018 EXTERNAL USE Page 2 f 8 Next revisin due: 28/06/2022 HARDCOPY IS UNCONTROLLED Pwerlink Queensland

3 ASM-STR-A Versin: 2.0 Equipment Strategy Fr Earthing Transfrmers Strategy 1. Intrductin 1.1 Purpse Equipment Strategies dcument Pwerlink s visin fr equipment technlgies, t prvide bth Pwerlink and Suppliers with cnsistent planning and prject management platfrms fr the life f the strategy. The Equipment Strategy fr Earthing Transfrmers has been develped with input frm the teams f Asset Management, Engineering, Netwrk Maintenance, and Prcurement. 1.2 Scpe This dcument cvers the equipment requirements fr earthing transfrmers fr use in new substatins, substatins requiring majr refurbishment r rebuild, and existing substatins requiring minr refurbishment, augmentatin r maintenance replacement. This scpe is applicable fr mineral il filled, cre type, distributin class transfrmers with rated vltages f 11kV, 22kV and 33kV. Secndary system cntrl and prtectin philsphy strategies have nt been addressed within the scpe f this dcument. The equipment strategy will be reviewed n a regular basis t incrprate changes at the mst pprtune time. This equipment strategy will have a life f five years with a significant review in the furth year. During the review, technlgies which have matured during the life f the strategy will be incrprated if they have merit in Pwerlink s cntext. 1.3 References Dcument cde AS AS/NZS AS1028 Dcument title Standards Australia (2003) Pwer Transfrmer Minimum Energy Perfrmance Standard (MEPS) Requirements fr Distributin Transfrmers Standards Australia (2014) Pwer Transfrmers General Standards Australia (1992) Pwer reactrs and earthing transfrmers 1.4 Defined terms Terms SAP Definitin Sftware package used fr cmputerised maintenance management system and asset register 1.5 Mnitring and cmpliance This equipment strategy will guide develpment f the technical specificatin. The success is mnitred thrugh regulatry infrmatin ntice, annual reprting and SAP recrds review f installed equipment. The success f this strategy is measured by mnitring life cycle csts as well as availability and service histry assciated with this equipment. The minimum recrds required are: Technical specificatin Tender evaluatin reprt Current versin: 28/06/2018 EXTERNAL USE Page 3 f 8 Next revisin due: 28/06/2022 HARDCOPY IS UNCONTROLLED Pwerlink Queensland

4 ASM-STR-A Versin: 2.0 Equipment Strategy Fr Earthing Transfrmers Strategy Perid cntract Purchase rders SAP equipment recrds Operatin and Manufacturer Manual Nameplate details Factry Acceptance Test Reprt Shrt-Circuit design type test reprt 1.6 Risk management The risks cnsidered in the develpment f this strategy are: Netwrk Operatins Risk risk related t the increased prbability f damages caused by high grund fault currents leading t the unplanned netwrk utages and their impact n custmers and stakehlders. Safety Risk risk assciated with increased prbability f exceeding allwable step and tuch ptential and increased prbability f equipment damage resulting in fire r destructin causing injuries t persnnel r public. Envirnmental Risk related t il leaks and ptential f damages caused by fire. Financial and Cntractual Risk risk assciated with ptential equipment damage r inability t make warranty claims, request access t adequate technical supprt and spares, increased maintenance csts, additinal capital investment csts. 2. Strategy The dcument expresses Pwerlink s visin in terms f the equipment perfrmance requirements. It is nt a detailed cntract specificatin. The Visin The fllwing are the main features f the Asset Management visin fr earthing transfrmers: Annual peratin and maintenance csts less than 0.1% f the equipment replacement value. Very high availability, reliability, and cst cmpetitiveness n a whle f life basis. Minimal rutine maintenance mainly based n visual inspectin with additinal testing/service requirements kept t minimal. N service interval fr the life f the asset based n a 40 year life span. Fcus n perfrmance f the whle earthing transfrmer rather than design f individual elements r cmpnents. Reliability centred design principles incrprated. Safety in design principles incrprated. Safety and the envirnment The design, peratin and maintenance f earthing transfrmers shuld align with the principles f Safety in Design and cmply with Asset Management and legislative requirements fr safety, envirnmental and cultural & wrld heritage cmpliance. Current versin: 28/06/2018 EXTERNAL USE Page 4 f 8 Next revisin due: 28/06/2022 HARDCOPY IS UNCONTROLLED Pwerlink Queensland

5 ASM-STR-A Versin: 2.0 Equipment Strategy Fr Earthing Transfrmers Strategy The prbability f explsive failure shuld be as lw as pssible. Failure mdes shuld be nn-life threatening and as safe as pssible fr persnnel wrking in the substatin yard and the general cmmunity. Where pssible, the use f prcelain in the transfrmer design shuld be excluded. Where pssible, the use f il shuld be kept t a minimum. Sund levels shuld be limited t an ecnmically minimum standard withut becming a majr design driver. Electrmagnetic interference shuld be limited in accrdance with the requirements f AS/NZS 2344 Limits f Electrmagnetic Interference frm Overhead AC Pwerlines and High Vltage Equipment Installatins in the Frequency Range 0.15 t 1000MHz. Maintenance Maintenance Level Earthing transfrmers shuld be designed and manufactured t require minimal intrusive maintenance and a minimum f rutine inspectins in their life cycle. The preferred technical slutin is adptin f fit and frget transfrmers requiring n maintenance fr 40 years. Equipment is t have: Negligible maintenance requirements, Least number f mving parts, Simple but rbust and reliable design, Lw electrical & thermal stresses, Mdularity f design, Free standing grund r ple munted units are preferred with prvisin fr adaptatin t suit pwer transfrmer tank munted arrangements ( transfrmer tank munted arrangement is t be avided wherever pssible), and Plug and Play terminatin cnnectins suitable fr cable cnnectin t the pwer transfrmer are preferred and earthing transfrmers will nt have cable bxes. Equipment Mnitring Only lcal temperature mnitring is required, n remte indicatin. Internal CTs are required. Pressure relief devices required belw il level fr the main tank (with alarm cntact). Ready t use facility t take il samples is required. 2.1 Prjected use f equipment Earthing transfrmers purchased in accrdance with this equipment strategy will be: Used t prvide an earth reference with earth fault current limiting capability, Supplied with a primary vltage f 11kV, 22Kv r 33kV, Be supplied withut secndary r auxiliary windings, Current versin: 28/06/2018 EXTERNAL USE Page 5 f 8 Next revisin due: 28/06/2022 HARDCOPY IS UNCONTROLLED Pwerlink Queensland

6 ASM-STR-A Versin: 2.0 Equipment Strategy Fr Earthing Transfrmers Strategy Prcured in a ple r grund munted arrangement with prvisin t be adapted t a pwer transfrmer tank munted arrangement if required and with aerial r plug in cable cnnectin bushings (aerial being preferred cnnectin). 2.2 Design philsphy Design requirements The key elements f the design philsphy fr an earthing transfrmer are: 1. Earthing transfrmer shrt time neutral current rating f 2475 Amps fr 2 secnds fr 11kV system r 8660 Amps fr 2 secnds fr 22kV system and 2858 Amps fr 2 secnds fr 33kV system. 2. Earthing transfrmer cntinuus neutral current rating f 150Amps fr 11kV system and 120 Amps fr 22kV and 33kV systems. 3. Cnnectin Grup ZN intercnnected star. 4. Zer sequence impedance as defined by the transfrmer specificatin. 5. Supplied with vltage surge prtectin. 6. The flux density shuld be such that the cre des nt saturate during a thrugh fault and a cnstant zer sequence impedance is maintained under thrugh fault cnditins. 7. T be f a prven shrt-circuit tested design. 8. Naturally cled. 9. Only lcal temperature mnitring is required, n remte indicatin. 10. Internal CTs are required. 11. Pressure relief devices required belw il level fr the main tank (with alarm cntact). 12. The main tank shall be hermetically sealed Service envirnment Pwerlink substatins may be lcated in areas that experience a ht, humid summer, high average temperatures, high r very high numbers f rainfall days and high r very high rainfall. These cnditins cmbined with the netwrk s prximity t the cast prduce high crrsin rates fr expsed cmpnents that are nt UV stabilised r adequately prtected frm the envirnment. The netwrk is als lcated in areas f high thunder-days with the ptential t expse high vltage plant t hazardus vltages which may impact n equipment and netwrk perfrmance. In additin the design and cnstructin have t be suitable fr installatin in cyclnic areas with high wind speeds Operating cntext The perating cntext fr Pwerlink earthing transfrmers will be; Testing and perating perfrmance t meet the requirements f AS/NZS / AS 2374 / AS Technlgies traditinally used by Pwerlink Pwerlink uses cre type, mineral il filled, distributin class transfrmers in substatin earthing transfrmer applicatins. Pwerlink has Pre-Apprved suppliers f bushings, il, cnductrs, cre steel, and pressure relief valves. The list is regularly reviewed and updated based n engineering evaluatin and in-service experience. Current versin: 28/06/2018 EXTERNAL USE Page 6 f 8 Next revisin due: 28/06/2022 HARDCOPY IS UNCONTROLLED Pwerlink Queensland

7 ASM-STR-A Versin: 2.0 Equipment Strategy Fr Earthing Transfrmers Strategy 2.4 Technlgies available nw The technlgies available fr the manufacture f earthing transfrmers are mature and have been refined and prven ver many years. Design changes t incrprate imprvements in technlgy can be shrt circuit tested t prve their perfrmance under fault cnditins. Distributin transfrmer manufacturers have an ptimised range f designs typically aligned with current utility perid cntracts. Earthing transfrmers are usually manufactured as il immersed transfrmers with a rectangular cre design. Oil types can include mineral, vegetable, synthetic and silicn fluid. Windings are manufactured frm aluminium r cpper cnductr that can be enamel r paper cvered r bare. Earthing transfrmers can be individually packaged r may be supplied in the frm f a supplementary winding n an auxiliary r pwer transfrmer. The earthing transfrmer munting style can be ple munt, grund munt r tank munted n a larger transfrmer. A range f sealing arrangements and surface preparatin methds & catings are available in an effrt t delay the nset f transfrmer defects assciated with il leaks and surface crrsin which may impact n the expected transfrmer life span. Earthing transfrmers will be manufactured t meet the requirements f AS/NZS / AS2374 / AS1028 as applicable. In accrdance with Gvernment legislatin, Pwerlink requires distributin class transfrmers t meet the requirements f AS Pwer Transfrmer Minimum Energy Perfrmance Standard (MEPS) Requirements fr Distributin Transfrmers. The Pwerlink Specificatin fr Earthing Transfrmers specifies additinal requirements aimed t ensure that reliable, lw maintenance devices are purchased. 2.5 Equipment strategy elements The Asset Management visin in perating and maintaining transfrmers is that earthing transfrmers include the fllwing main features: Mineral il immersed, Hermetically sealed and naturally cled, Lw lss, nn-amrphus steel cre, Steel tank, Pressure relief device fitted belw minimum il level, Manufactured by a reputable and prven supplier, Prvisin f internal tridal current transfrmers, Prvisin fr il sampling, Terminatin cnnectins suitable fr cable cnnectin are preferred. Technlgical advances in sealing arrangements and surface preparatin and catings are t be pursued pprtunistically where pssible t delay the nset f transfrmer defects assciated with il leaks and surface crrsin. Technlgical advances in winding design arrangements are t be pursued pprtunistically where pssible t delay the premature failure f the windings assciated with repetitive thrugh faults. All transfrmer cmpnents and materials including the active part, ancillary equipment, il, bushings and tank / enclsure must strictly cnfrm t the requirements detailed in the technical specificatin. Current versin: 28/06/2018 EXTERNAL USE Page 7 f 8 Next revisin due: 28/06/2022 HARDCOPY IS UNCONTROLLED Pwerlink Queensland

8 ASM-STR-A Versin: 2.0 Equipment Strategy Fr Earthing Transfrmers Strategy 2.6 Cncurrent investigatins: Cntinuus technlgical advancements in the manufacture and prcurement f transfrmer raw materials (steel, cnductr, insulatin, and il), sealing arrangements, surface catings, manufacturing tling / methds and design / mdelling tls are prevalent thrughut the industry. It is imperative that clse examinatin f the available technlgies be made t ensure that they meet Pwerlink requirements and adpt the mst apprpriate technlgy. The Equipment Strategy itself is t be reviewed in fur years t leverage the evlving technlgical advancements and t include service experience. 2.7 Summary This equipment strategy will be adpted fr all future requirements fr earthing transfrmers, unless therwise apprved fr specific and explicit reasns, s as t achieve the minimum whle f life cst as well as ensuring the benefits f ease f cmmissining, perating and maintenance are btained. Current versin: 28/06/2018 EXTERNAL USE Page 8 f 8 Next revisin due: 28/06/2022 HARDCOPY IS UNCONTROLLED Pwerlink Queensland