IEC TS 6291 6 Edition 1 0 201 7 04 TECHNICAL SPECIFICATION Photovoltaic modules – Bypass diode electrostatic discharge susceptibil ity testing IE C T S 6 2 9 1 6 2 0 1 7 0 4 (e n ) ® colour inside THI[.]
I E C TS 62 91 ® Edition 201 7-04 TE CH N I CAL SPE CI FI CATI ON colour i n si de Ph oto vol tai c m o d u l es – B ypass d i od e el ectrostati c d i sch arg e su scepti bi l i ty IEC TS 6291 6:201 7-04(en) testi n g TH I S P U B L I C AT I O N I S C O P Y R I G H T P R O T E C T E D C o p yri g h t © I E C , G e n e v a , Sw i t z e rl a n d All rights reserved Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either IEC or IEC's member National Committee in the country of the requester If you have any questions about IEC copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or your local IEC member National Committee for further information IEC Central Office 3, rue de Varembé CH-1 21 Geneva 20 Switzerland Tel.: +41 22 91 02 1 Fax: +41 22 91 03 00 info@iec.ch www.iec.ch Ab o u t th e I E C The International Electrotechnical Commission (I EC) is the leading global organization that prepares and publishes International Standards for all electrical, electronic and related technologies Ab o u t I E C p u b l i ca t i o n s The technical content of IEC publications is kept under constant review by the IEC Please make sure that you have the latest edition, a corrigenda or an amendment might have been published I E C Catal o g u e - websto re i ec ch /catal o g u e The stand-alone application for consulting the entire bibliographical information on IEC International Standards, Technical Specifications, Technical Reports and other documents Available for PC, Mac OS, Android Tablets and iPad I E C pu bl i cati on s search - www i ec ch /search pu b The advanced search enables to find IEC publications by a variety of criteria (reference number, text, technical committee,…) It also gives information on projects, replaced and withdrawn publications E l ectroped i a - www el ectro ped i a o rg The world's leading online dictionary of electronic and electrical terms containing 20 000 terms and definitions in English and French, with equivalent terms in additional languages Also known as the International Electrotechnical Vocabulary (IEV) online I E C G l o ssary - std i ec ch /g l o ssary 65 000 electrotechnical terminology entries in English and French extracted from the Terms and Definitions clause of IEC publications issued since 2002 Some entries have been collected from earlier publications of IEC TC 37, 77, 86 and CISPR I E C J u st Pu bl i sh ed - websto re i ec ch /j u stpu bl i sh ed Stay up to date on all new IEC publications Just Published details all new publications released Available online and also once a month by email I E C Cu stom er Servi ce Cen tre - websto re i ec ch /csc If you wish to give us your feedback on this publication or need further assistance, please contact the Customer Service Centre: csc@iec.ch I E C TS 62 91 ® Edition 201 7-04 TE CH N I CAL SPE CI FI CATI ON colour i n si de Ph oto vol tai c m od u l es – B ypass d i od e el ectrostati c d i sch arg e su scepti bi l i ty testi n g INTERNATIONAL ELECTROTECHNICAL COMMISSION ICS 27.1 60 ISBN 978-2-8322-41 47-9 Warn i n g ! M ake su re th a t yo u o btai n ed th i s pu bl i c ati o n fro m an au th ori zed d i stri bu to r ® Registered trademark of the International Electrotechnical Commission –2– I EC TS 6291 6: 201 © I EC 201 CONTENTS FOREWORD Scope N orm ati ve references Term s, defi n iti ons and abbrevi ated term s General Sam pl in g 6 Test equ ipm ent 7 Test m ethod 7 Preparati on 7 Surg e testi ng 8 Data an al ysis 8 Two-param eter Weibu ll distri bution for an al yzi n g voltag e to fai l ure 8 Recom m ended m edi an rank estim ation for th e cu m u lati ve distri bution Recom m ended form for data anal ysis by least squ ares l in ear regressi on 9 Report Ann ex A (inform ati ve) G u idelin es for appl ication 1 Ann ex B (inform ati ve) Exam pl e of application Fig u re – Exam pl e of a test setup for bypass diodes Fig u re B – Chart of sam ple data Tabl e – Data org ani zati on for l east squ ares regression Tabl e B – Exam pl e of data anal ysis I EC TS 6291 6: 201 © I EC 201 –3– I NTERNATI ON AL ELECTROTECH NI CAL COMMI SSI ON PHOTOVOLTAIC MODULES – BYPASS DIODE ELECTROSTATIC DISCHARGE SUSCEPTIBILITY TESTING FOREWORD ) Th e I n ternati on al El ectrotechn i cal Com m i ssi on (I EC) i s a worl d wi d e org an i zati on for stan dardi zati on com pri si n g al l n ati on al el ectrotech ni cal com m i ttees (I EC N ati onal Com m i ttees) The obj ect of I EC i s to prom ote i n ternati on al co-operati on on al l q uesti on s concern i n g stand ardi zati on i n th e el ectri cal an d el ectron i c fi el ds To thi s en d and i n addi ti on to other acti vi ti es, I EC pu bl i sh es I n ternati on al Stan dards, Tech n i cal Speci fi cati ons, Tech ni cal Reports, Pu bl i cl y Avai l abl e Speci fi cati ons (PAS) an d Gu i des (h ereafter referred to as “I EC Publ i cati on (s) ”) Th ei r preparati on i s entru sted to tech n i cal com m i ttees; an y I EC N ati on al Com m i ttee i nterested i n th e su bj ect deal t wi th m ay parti ci pate i n th i s preparatory work I nternati on al , g overn m ental an d n on g overn m ental org an i zati ons l i si n g wi th th e I EC al so parti ci pate i n th i s preparati on I E C col l aborates cl osel y wi th th e I n tern ati onal Org an i zati on for Stan d ardi zati on (I SO) i n accordan ce wi th di ti on s determ i ned by ag reem en t between th e two org an i zati on s 2) Th e form al deci si on s or ag reem en ts of I EC on tech ni cal m atters express, as n earl y as possi bl e, an i nternati on al sen su s of opi ni on on th e rel evant su bj ects si n ce each tech ni cal com m i ttee h as representati on from al l i n terested I EC N ati on al Com m ittees 3) I EC Pu bl i cati ons h ave th e form of recom m endati on s for i ntern ati on al u se an d are accepted by I EC N ati onal Com m i ttees i n th at sense Whi l e al l reasonabl e efforts are m ade to ensure th at th e tech n i cal content of I EC Publ i cati on s i s accu rate, I EC can n ot be h el d respon si bl e for th e way i n wh i ch th ey are used or for an y m i si nterpretati on by an y en d u ser 4) I n order to prom ote i n tern ati onal u ni form i ty, I EC N ati on al Com m i ttees un d ertake to appl y I EC Pu bl i cati on s transparentl y to the m axi m um extent possi bl e i n th ei r n ati onal an d reg i on al publ i cati on s An y di verg en ce between an y I EC Pu bl i cati on an d the correspon di ng nati on al or reg i on al pu bl i cati on sh al l be cl earl y i n di cated i n the l atter 5) I EC i tsel f d oes n ot provi de an y attestati on of form i ty I n depend ent certi fi cati on bodi es provi de form i ty assessm ent servi ces an d, i n som e areas, access to I EC m arks of form i ty I EC i s not respon si bl e for an y servi ces carri ed out by i n d epen den t certi fi cati on bodi es 6) Al l u sers sh ou l d en su re th at th ey h ave the l atest edi ti on of th i s publ i cati on 7) N o l i abi l i ty shal l attach to I EC or i ts di rectors, em pl oyees, servants or ag en ts i ncl u di n g i n di vi du al experts an d m em bers of i ts tech n i cal com m i ttees and I EC Nati on al Com m i ttees for any person al i n j u ry, property d am ag e or other dam ag e of any n atu re wh atsoever, wheth er di rect or i n di rect, or for costs (i n cl u d i n g l eg al fees) and expenses ari si ng out of th e pu bl i cati on, u se of, or rel i an ce upon, th i s I EC P ubl i cati on or an y oth er I EC Publ i cati ons 8) Atten ti on i s drawn to th e N orm ati ve referen ces ci ted i n th i s pu bl i cati on U se of th e referenced publ i cati on s i s i n di spensabl e for th e correct appl i cati on of th i s publ i cati on 9) Atten ti on i s drawn to th e possi bi l i ty th at som e of th e el em en ts of th i s I EC Pu bl i cati on m ay be th e su bj ect of paten t ri g hts I EC sh al l n ot be h el d responsi bl e for i denti fyi ng an y or al l such paten t ri g h ts The m ain task of I EC techn ical com m ittees is to prepare I ntern ati onal Stan dards I n excepti onal circum stances, a tech n ical com m ittee m ay propose th e publ icati on of a tech n ical specification wh en • th e requ ired su pport can not be obtain ed for th e pu bl ication of an I n tern ati onal Stan dard, despite repeated efforts, or • th e subj ect is stil l u nder tech n ical developm en t or wh ere, for an y oth er reason , th ere is th e future but no im m edi ate possi bi li ty of an agreem ent on an I ntern ati on al Standard Techn ical specificati ons are subj ect to review withi n th ree years of publicati on to decide wh eth er th ey can be tran sform ed in to I n tern ati onal Stan dards I EC TS 6291 6, wh ich i s a tech n ical specificati on , has been prepared by com m ittee 82: Solar ph otovol taic system s I EC techn ical –4– I EC TS 6291 6: 201 © I EC 201 The text of th is tech n ical specification is based on th e fol lowi n g docum en ts: Enqui ry draft Report on voti n g 82/1 059/DTS 82/1 259/RVDTS Fu l l i nform ation on th e voting for the approval of this techn ical specification can be fou n d in th e report on voti n g i ndicated i n th e above tabl e This docum en t h as been drafted in accordance wi th th e I SO/I EC Directi ves, Part The com m ittee h as deci ded that the ten ts of th is pu blicati on wi ll rem ain unch ang ed u nti l th e stabil i ty date in dicated on the I EC website un der "h ttp://webstore iec ch " i n th e data related to th e specific pu blication At th is date, th e publicati on wi ll be • • • • • transform ed in to an I n ternation al stan dard, reconfi rm ed, wi thdrawn , repl aced by a revised edi ti on, or am ended A bi l in g ual versi on of th is pu bl icati on m ay be issu ed at a l ater date IMPORTANT – The 'colour inside' logo on the cover pag e of this publication indicates that it contains colours which are considered to be useful for the correct understanding of its contents Users should therefore print this document using a colour printer I EC TS 6291 6: 201 © I EC 201 –5– PHOTOVOLTAIC MODULES – BYPASS DIODE ELECTROSTATIC DISCHARGE SUSCEPTIBILITY TESTING Scope This docum en t describes a discrete com pon ent bypass diode electrostatic disch arge (ESD) im m un ity test an d data anal ysis m eth od Th e test m ethod described subj ects a bypass di ode to a progressive ESD stress test and th e an al ysis m ethod provi des a m ean s for an al yzi n g an d extrapol ati n g th e resu ltin g fai lu res usin g the two-param eter Weibul l distribu ti on fu nction I t is th e obj ect of th is docum en t to establish a com m on and reproduci bl e test m eth od for determ in in g diode surg e voltag e tol erance consisten t with an ESD even t during the m anufacturing , packag i n g , transportation or instal l ati on processes of PV m odu l es This docum en t does n ot purport to address causes of el ectrostatic disch arg e or to establ ish pass or fai l l evels for bypass di ode devices I t is th e responsibi l ity of th e u ser to assess the ESD exposure l evel for their particu l ar circum stances Th e data gen erated by th is procedure m ay su pport qu al ification of n ew desi g n types, qu al ity control for i ncom ing m ateri al, and/or identify th e n eed for additi onal ESD controls in the m anu facturin g process Finall y, this docum en t does not appl y to l arg e energ y surg e events such as direct or i ndirect lig h tn i ng exposure, u ti li ty capacitor bank switch ing events, or th e l ike Normative references The foll owi n g docum ents are referred to i n th e text in such a way that som e or al l of their ten t constitutes requ irem ents of th is docum ent For dated references, on l y th e edition cited appl i es For u ndated references, th e latest edition of the referenced docum en t (incl ud in g an y am endm en ts) appli es Electromagnetic compatibility (EMC) – Part 4-2: Testing and measurement techniques – Electrostatic discharge immunity test I EC 61 000-4-2:2008, Terms, definitions and abbreviated terms For th e purposes of thi s docum en t, the term s an d defi ni ti ons of I EC TS 61 836 an d th e fol lowi ng appl y I SO an d I EC m ain tai n term in olog ical databases for use in stan dardi zati on at th e fol l owing addresses: • I EC Electropedi a: avai labl e at h ttp://www el ectropedia org / • I SO On l in e browsi n g platform : avai l abl e at http://www iso org/obp 3.1 DUT device u nder test 3.2 contact discharg e method m ethod of testi ng in wh i ch th e electrode of the test g enerator is kept in contact with the DUT an d the disch arg e is actu ated by th e discharg e with in th e gen erator –6– I EC TS 6291 6: 201 © I EC 201 Note to entry: I n thi s d ocu m ent, the tact i s to th e el ectri cal l ead of th e D UT wi th no i nterven i n g el ectri cal i nsu l ati on m ateri al 3.3 diode check function usag e of a m ul tim eter wi th diode fu ncti on ch eck to verify th e di ode is fu ncti on al, short or open 3.4 direct application application of th e test su rge directl y to the DU T Note to en try: I n th i s techn i cal speci fi cati on , th e surg es are di rected to bypass d i odes for ph otovol tai c appl i cati on s ou tsi de of th e actual ph otovol tai c appl i cati on (e g , DU T are tested ou tsi de of th e j u n cti on box and are not associ ated wi th th e ph otovol tai c m odu l e i tsel f when ch aracteri zed ) 3.5 surg e relaxation time am oun t of tim e necessary for th e DUT to th erm al l y stabi li ze in th e event th at su rge appl ication creates l ocal ized reg ions of h eat g en erati on General Produ ction lin e qual ity excursions due to bypass diode fai lu re h ave been observed in the PV m odu le m an ufacturi ng process du e to ch an g es i n the electrostatic disch arg e (ESD) suscepti bil ity of bypass diodes Th is docu m en t provi des a m eth od to evalu ate th e su scepti bi lity of bypass diodes to fai l du e to ESD even ts that m ay occu r in th e production , transport or instal lation of ph otovol taic (PV) m odu l es ESD events occu r when ever th ere is tact, or su fficientl y close proxim ity between obj ects of differen t el ectrostatic ch arg e Th e m ag n itu de of th e ESD even t is a function of th e ch arg e difference between th e obj ects an d th e im pedance associ ated with the charg e transfer Of specific interest in th is docum en t are relativel y l ow energ y, sh ort-duration surges that m ay be associ ated wi th th e m an ufacturing process, testin g, or i nstall ati on events where th e bypass diodes are directl y exposed to an ESD event Several stan dard ESD m odels exist for th e evalu ation of surg e im m un ity Th is docu m en t adopts th e m odel provi ded by I EC 61 000-4-2:2008 th at provides a m eth od for assessi ng dam ag e to el ectrical and electron ic equ ipm ent su bj ected to static electrici ty discharg es from operators directl y, and from personn el to adj acen t obj ects Sampling Ten u ncon diti on ed di odes are requ ired for th is test Several factors shou ld be consi dered wh en m akin g sam pl e sel ecti on : • Di ode types sh al l be i dentical Different diode types wil l not provide usefu l surge im m unity i nform ation – Each diode type th at was tested duri ng th e devel opm en t of th is procedure yielded a different fail ure distri bution in dicating th at m ixed type testin g wou l d not be m ean in gfu l • Di ode date codes an d factory l ocati on sh ou l d be i den tical – The best ch aracterizati on of a diode's su rge im m un ity wi ll be obtai ned wh en th e di odes are from one m an ufacturi ng locati on and from a specific m an ufactu rin g batch – Com parison of th e fail u re distri buti ons th at resu lt from appl yi n g th is procedu re to several different date codes m ay provide th e user with a qu al itati ve u nderstan di n g of th e diode m an ufacturer's qu al ity control from a su rg e im m unity perspective Sim i lari ty of resu lts from differen t date codes wou ld in dicate a tig hter qu ali ty control m eth od • Diodes are tested in dependentl y and outsi de of a m odu le or j u ncti on box The leads sh al l be in th e form requ ired before assem bl y i nto a j u n cti on box I EC TS 6291 6: 201 © I EC 201 – –7– Lead trim m in g or lead form in g operations sh ou l d be done before testin g as th ese operations can create stress on th e diode di e th at m ay h ave an im pact on th e diode's su rg e im m u nity Test equipment Test equ i pm ent sh all conform to the requ irem en ts stated i n I EC 61 000-4-2:2008, Clause usin g the disch arge electrode for tact discharges The discharg e retu rn conn ection from th e surg e g en erator sh al l be conn ected to a groun di ng block desi gn ed to accom m odate th e DUT sam ples, takin g into accou nt spaci n g requ irem ents th at m ay be requ ired for form ed leads as sh own in Fig u re Mu ltiple DU T sam pl es m ay be conn ected to a sin g l e grou n din g block The equi pm en t sh all be capabl e of posi tive pol arity su rg es (wi th respect to earth grou n d) , ducted in a sin g l e-su rge m ode, and wi th a vol tag e th at can be i ncrem ented in kV steps from kV to a recom m ended 30 kV or hi g her capabi lity Equ i pm ent havi ng a surge vol tag e lim itation th at is less th an 30 kV m ay be used, but th is m ay l im it DUT fai lu re i nform ation an d subsequ ent data an al ysis for a very surg e-resistan t DU T Groun d bl ock Bypass di odes typi cal ESD g u n g rou n d conn ecti on IEC Figure – Example of a test setup for bypass diodes Test method 7.1 Preparation a) Place u ncon diti oned DUTs in to an electrical l y grou n ded fixtu re such th at th e DU T an ode is grou n ded an d the cathode is exposed and accessible (Figu re ) b) U se a m ul tim eter with di ode-ch eck function ali ty to verify th at all DU Ts are functional in th e forward bias directi on an d th at non e are sh orted i n th e reverse bi as directi on I n th e event th at a DU T is fou n d to be in a n on-operati on al state before test, repl ace as n ecessary so th at ten fu ncti onal u n its are su bj ected to th e surg e testing –8– I EC TS 6291 6: 201 © I EC 201 c) Place a contact probe ti p (I EC 61 000-4-2: 2008, Fi gu re 3b) onto a surg e gen erator wh ose intern al im pedance conform s to th e 330 Ω , 50 pF requi rem en ts d) Set the in i tial surg e voltage to kV i n a posi ti ve polari ty wi th respect to earth groun d e) Ensure equi pm en t is set to provi de on l y a sin g le su rg e per operation f) Record th e am bi ent tem peratu re and rel ative hum i di ty durin g the testi ng peri od For com parison purposes, 20 °C ± °C an d 50 % ± % RH are recom m ended 7.2 Su rg e testing a) Con duct on e surg e on th e first DUT Th e tip of th e tact probe sh al l be i n tact with th e electrical leads as cl ose to th e DU T protecti ve bod y as possible Keep track of tim e elapsed as each DUT is tested b) Repeat step a) on th e next DUT u n ti l al l ten have been tested once c) Repeat surge testi n g, steps a) an d b) , u nti l each DU T has accum ul ated a total of ten i ndi vidu al surg es Wait, if necessary, to ensu re th at s, or m ore, of surg e relaxati on tim e has el apsed before repeating th e su rge test on an y DU T d) U se a m ultim eter with a diode-ch eck functi on to determ in e if al l DU Ts are function al i n the forward bias direction an d n ot exh ibit a sh ort-circui t in eith er forward or reverse bias Rem ove an y di odes th at have fai led from the test setu p an d note the surg e voltag e at wh ich th e fail ure occu rred e) I ncrease th e surge equ i pm ent potenti al by kV (positive pol ari ty with respect to earth grou nd) from i ts previous setti ng f) Place all rem ain ing diodes back in to their starti ng ori en tation (if n ecessary) an d repeat steps a) to d) g) Repeat step f) , increasin g su rg e equ i pm ent voltag e by kV steps u n ti l 30 kV or th e testi n g capabil i ty of th e su rge equ ipm en t is reached , wh ichever is sm al ler 8.1 Data anal ysis Two-parameter Weibull distribution for anal yzing voltag e to failu re The two-param eter Weibu ll cu m ul ative distribu tion of th e voltag e to DUT fai lure is written as: 퐹 (푉 ) = − exp �− �푉훼 � 훽 � (1 ) wh ere F( V) is the fracti on of al l u n its in th e popu l ati on wh ich fail by V su rg e voltage; β α is the Weibul l distribu ti on sh ape param eter; is th e Weibu ll distribu ti on characteristic life param eter, or th e su rg e voltag e corresponding to F = – /e = 0, 632 A straig ht l in e form ul a of slope of form ula (1 ) twi ce yi el di ng : β can be form ed by taki n g th e n atural l og arithm of both sides ln � ln � 푉 � � = 훽 ln � � 훼 −퐹 (푉 ) (2) wh ich can be rearran ged as: ln � ln � � � = 훽 ln(푉 ) − 퐹 (푉 ) − 훽 ln(훼 ) (3) I EC TS 6291 6:201 © I EC 201 –9– Arran g em ent of the experim en tal data i nto two grou ps, th e indepen den t variabl e ln (V) on the ri gh t h an d side an d th e depen den t vari abl e sh own on th e left han d si de of form u la (3) al lows for a l east-squ ares li n ear regression tech n iqu e th at resu lts i n an estim ati on of th e slope β and th e intercept β ln( α ) from wh ich, th e characteristic l ife, α , can be estim ated 8.2 Recommended medi an rank estim ation for th e cumulative di stribu tion Several m eth ods are avail able to estim ate th e cum ul ati ve distri buti on fu ncti on On e m eth od th at easil y l ends itself to han d or spreadsh eet calcu lation is m edian rank estim ation I n order to calcu late th e l eft h and si de of form ula (3) , an estim ate for the cu m ul ative distribu tion , F( V) is requi red Th is docum ent uses the m edi an rank estim ate defin ed as: �( 퐹 푉) = 푂푖 − ,3 푛+0 , (4) wh ere Oi is the rank order positi on of the failu re for th e ith data point, when the data poi n ts are ranked in order from earli est fai lure to l atest fai lure; n is the total n u m ber of data poin ts 8.3 Recommend ed form for data analysis by least squ ares li near reg ression Medi an rank estim ati on d ata m ay be plotted m an u all y or throu g h a sim ple spreadsheet m odel Com pu ter program s are also avai labl e an d m ay be used to present data and estim ate u nkn owns in form u la (1 ) I n th e m eth od provi ded bel ow, th e voltag e at fai l ure, V, com es from th e test result and cu m u l ati ve distri bu tion estim ate, 퐹� (푉 ) , com es from form ula (4) Th e ri gh t m ost col um ns are calcu l ated as indicated an d th e resul tin g x i and yi m ay be pl otted on l i near graph paper, or on a spreadsheet prog ram A l in ear reg ressi on is then fi t throu g h th ese poi nts See Table Table – Data org anization for least squ ares reg ression Fail ure ord er 푭� (푽) , formul a (4) Vol tag e at fail ure, V in kV l n (V) x i for least squares 퐥퐥 �퐥 � 퐥 ퟏ �� ퟏ − 푭� (푽) yi for least squ ares The best estim ate for a li near fit of x i and yi is provided by form ul a (5) : 푦� = 푚푚 + (푦� − 푚 ̅) (5) 푚 wh ere 푚̅ = an d ∑ 푛= 푥푖 푖 푛 푦 � ∑ 푖= 푛 = 푛 푦푖 (6) – 10 – I EC TS 6291 6:201 © I EC 201 푚 = 푛 ∑ =1 ∑푥푖 푦 −푥2∑− =∑1 푥 푛 푖 푖 푛 푛 푖 =1 � 푖 푛 푖 � 푖� � ∑ 푛푖= 푦푖 � = 푥푖 � 푛 푖 (7) The reg ression m ay be used to extrapolate the resu lts to different levels of appli ed surg e voltag e oth er th an th ose used i n the experim ental program Report The report shal l contai n i nform ation n ecessary to reproduce test resu lts an d th e details of the sam pl es tested Specificall y, m ake note of the fol l owing : • I dentificati on of the DU T an d date codes associ ated wi th th e sam ples tested For th e pu rpose of i n terl aboratory com parison, th is i nform ati on m ay be m ade gen eric • Test resu lts and g raph inclu din g m eth od or prog ram used to obtai n th ose resu lts (e g , 3) • I dentificati on of test equ i pm ent by bran d, m odel and seri al n u m ber • Cal i bration i nform ati on or m eth od u sed to val idate data • Actu al en vironm en tal condi tions of am bi ent tem perature an d relati ve hum i dity duri n g th e testin g period • An y effects observed with th e DUT duri ng th e cou rse of testi ng if oth er than operati onal or fai lure in an electricall y short-circu it (e g , open-circu it, cracked, etc ) • Pictu re of an y fai led DU T, bu t on l y i n the event the fai l ure can be visu all y observed from chan ges in th e appearan ce • Ration ale for an y devi ations used in the test m eth od I EC TS 6291 6: 201 © I EC 201 – 11 – Annex A (informative) Guidelines for application Qu al i ty excursions h ave been observed in ph otovoltaic m odu le m anufacturi ng l in es that h ave been traced to batch fai l ure of bypass diodes I t was observed th at th e m ajority of fai lures occurred duri ng th e m an u factu ri ng assem bl y process i tself, h owever, a sm all percentage of m odu les that seem in g l y had fu ncti onal diodes on sh ipm en t were foun d i n th e field wi th fai l ed diodes su g gestin g th at dam ag e h ad occurred duri ng transport, i nstal l ati on , or as a consequ ence of cum ul ati ve dam ag e suffered from the m anufactu rin g throu gh i nstallation process Th is type of diode fail ure differs si g nifi can tl y from l i gh tn i n g- in duced di odes fai lu re dam ag e and is ch aracteri zed by i n dividual m odu le di ode fai l ure versus the failu re of m ost diodes associated with one or m ore source circu its i n the PV array This testi ng specification establ ishes th e diode's surg e tol erance voltage consisten t with an ESD even t an d m ay be usefu l for on e or m ore of the foll owi n g el em en ts of a m an ufacturi ng qu al ity system : • I ncom in g qu al ity trol • As part of either a control program plan or com pli an ce verification pl an as requ ired in I EC 61 340-5-1 :201 • Establish i ng th e m in im um requ ired level of di ode surge tolerance for a particu l ar facil ity if th is test specificati on is com bined wi th peak ESD voltag e ch aracteri zation equ i pm ent su ch as th e 3M EM E ye – 12 – I EC TS 6291 6: 201 © I EC 201 Annex B (informative) Example of application I n th e exam pl e bel ow, a set of ten diodes are tested accordin g to th e test m ethod descri bed i n Cl ause The data, anal yses and applicati on are shown i n Table B and Fi gu re B below Table B.1 – Example of data an alysis Fail ure ord er Vol tag e at fail ure, V in kV F(V), Median rank l n(V) l n{ln[1 /(1 -F(V))] } 20 0, 067 3, 00 –2, 66 20 0, 63 3, 00 –1 , 72 20 0, 260 3, 00 –1 , 20 25 0, 356 3, 22 –0, 82 25 0, 452 3, 22 –0, 51 30 0, 548 3, 40 –0, 23 ∑ xi n m= = 3,1 38 ∑ yi n = –1,1 92 n∑ in=1 xi yi – ∑ in=1 xi ∑ in=1 yi n∑ n x – i =1 i ∑ n x i =1 i = 4,366 y = mx + ( y – mx ) = 4,366 x – 4,892 0, 00 ln { l n [ /(1 – F( V) ) ] } –0, 50 –1 , 00 –1 , 50 –2, 00 –2, 50 –3, 00 2, 90 3, 00 3, 3, 20 ln 3, 30 ( V) Figu re B.1 – Ch art of sample data 3, 40 3, 50 IEC I EC TS 6291 6: 201 © I EC 201 – 13 – Based u pon th e an al ysis, i t is estim ated th at wh en placed in an en vironm en t wh ere kV ESD even ts are present, th e fracti on of un i ts fai li ng , F, in a larg e popu l ati on woul d be approxim atel y parts per m il lion _ INTERNATIONAL ELECTROTECHNICAL COMMISSION 3, rue de Varembé PO Box 31 CH-1 21 Geneva 20 Switzerland Tel: + 41 22 91 02 1 Fax: + 41 22 91 03 00 info@iec.ch www.iec.ch