SPLN 7C - 1978 [PDF]

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c 0 r r r s s r 0 rE{t r c T R 0 T E G H Nt tN0TuEER N A T t 0 N A L E - lS0) (affili6e i l'0rganisation Internationale de Normalisation R E C ( ) M M A I I D A T ID t )E NL A C E I



I T T E R } I A T I ( ) NEALLE G T B O T N E ICCHA LC ( M ) M I SS I O N - lS0) (affiliated to the International 0rganization forStandardization IECREC()MMENDATIt)N



Publication 99-l Deuxidm dd e i t i o -n S e c o nedd i t i o n



1970



Parafoudres partie:Parafoudres pourrdseaux Prami0re i r6sistance variable d courant alternatif



Lightning arreslers Parll: lrlon-linear typearresters fora.c.systems resistor



- Copyright - allrights reserved Droits r6servds dereproduction



Internationale Bureau Electrotechnique Central dela Commission 1, ruedeVaremb6



Suisse 6endve,



C. D. U./ U. D. G. : 621.316,933 .I 1l .s.0t1.222.01 .001.4-777



C()MMISSIE ( l IN T G T R ( l T E C H N I IONUTEE R N A T I ( } N A L E - lS0) (affili6e d l'0rganisation Internationale deNormalisation R E C l l M M A N D A TDI (El IL{A C E I



I N T E B N A T I ( l NEALLE G T R ( } T E C H N CI C ( )AML M I S S I ( } N - lS0) (affiliated to theInternational 0rganization forStandardization IECREC(lMMEIIDATItlN



Publication 99-l Deuxidme ddition- Second edition



1970



Pa rafoud res partie:Parafoudres Premi0re pourreseaux i rfsistance variable i courant alternatif



Lightning arresters



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Partl: Non-linear resistor typearresters for a.c.systems i



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P E R P { ] S TA. q{ K , e i " l t $ A Tp r l y E L f i l t x . { { i { r : { t t . , t r ,{ { t r $ T R , { ! r



- all rightsreserved - Copyright Droits dereproduction r6serv6s Aucunepartie de cette publicationne peut dtre reproduite ni utilisdesous q u e l q u ef o r m e q u e c e s o i t e t p a r a u c u n p r o c 6 d 6 , 6 l e c t r o n i qouue m 6 c a nique,y comprisla photocopie et les microfilms, sansI'accord dcritde l'6diteur.



No part of this publicationmay be reproducedor utilizedin any form or by any means,electronicor mechanical, includingphotocopying and microlilm,without permissionin writing f rom the publisher.



Bureau Central de la Commission Electrotechnique lnternationale '1,



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CONTENTS Page



FonewoRo



.



5



PREpRcr



.



5



SrcrroN ONE -



GpNBnar



Clause l. 2.



7 7



Scope Normal service conditions



SEcrroN Two -



DnnrNrrroNs .



3-49.



SEcnoN TsnEE 50. 51. 52. 53.



bENtIncATroN



Arrester identification Standardvoltageratings Standardrated frequencies Standardnorninaldischargecurrents.



. . . .



Sncuox Foun 54.



7



1 1 1 1



7 7 7 7



AnnEsrER cLASsrFrcATroN



Arresterclassification



.



1.7



SEcrroN Frve 55. 56. 57. 58.



. . . .



Test samples and measurements Power-frequency voltage tests . Wet tests Polluted housins test



SrcrroN Srx 59. 60. 61. 62. 63. 64. 65. 66.



General Power-frequencyvoltage sparkovertests Voltageimpulsesparkovertests Residualvoltagetest. Current in-rpulsewithstand tests Operating-dutytest Pressure-relieftests Testsof arresterdisconnectors SEcrroN



67. 68.



Routine tests Standard acceptancetests



Typr



7 9 9 1



rESTS (onsrcNTESTs)



. 2 3 . 2 3 ,)5 ,)o



:



. 31 . 3 7 39 . 4 3



ROUTTNE TESTS AND ACCEPTANCE TESTS



. . ' . . . . . . . . . ' .



A p p r : o r x A -- Typical circuit for operating-dutytest (Clause64) B - Abnormal serviceconditions C - Guide to the application of non-linear resistortype lightning arrestersfor a.c. systems D - Proposalsfor the artificial pollution testing of lightning arresters E -



1 t 1 2



Typical circuit for a distributed-constantimpulse generatorfor the long-duration current (Sub-clause 63.3)



47 47



.53 57 59 6l 73



- 5 -



TNTERNATIONAL



ELECTROTECHNICAL



COMMISSION



LIGHTNING ARRESTERS Part L: Non-linearresistortype arrestersfor a.c. systems



FOREWORD 1) The formal decisions or agreements of the IEC on technical matters, prepared by Technical Committees on which all the National Committees having a special interest therein are represented, express, as nearly as possible, an international consensus of opinion on the subjects dealt with. 2) They have the form of recommendations for international use and they are accepted by the National Committees in that sense. 3) In order to promote this international unification, the IEC expresses the wish that all National Committees having as yet no national rules, when preparing such rules, should use the IEC recommendations as the fundamental basis for these rules in so far as national conditions will permit. 4) The desirability is recognized of extending international agreement on these matters through an endeavour to harmonize national standardization rules with these recommendations in so far as national conditions will permit. The National Committees pledge their influence towards that end.



PREFACE This Recommendationhas been prepared by IEC Technical Committee No. 37, Lightning Arresters. It forms the secondedition of Publication99-l and supersedes the first edition issuedin 1958. Drafts were discussedat meetingsheld in Bucharestin 1962,in Venicein 1963,in Aix-les-Bainsin 1964, in Tokyo in 1965and in Paris in 1967. As a result of this latter meeting,a new draft was submittedto the National Committeesfor approval under the Six Months' Rule in May 1968. The following countriesvoted explicitly in favour of publication: Austraiia Belgium Canada Czechoslovakia Denmark Finland F rancc lran I srael Italy



Netherlands Norway Poland South Africa Switzerland Turkey Union of Soviet SocialistRepublics United Kingdorn Yugoslavia



7 -



LIGHTNING ARRESTERS Part L: Non-linearresistortype arrestersfor a.c. systems SECTION ONE



GENERAL



Scope This Recommendation applies to surge protective devicesdesignedfor repeated operation to limit voltage surgeson a.c. power circuits and to interrupt power follow current. In particular, it applies to lightning arrestersconsisting of single or multiple spark gaps in serieswith one or more non-linear resistors.



2.



Normal service conditions Lightning arresters which conform to this Recommendation shall be suitable for operation under the following normal serviceconditions: 'C (-40 oF to 'C to + 104"F). +40 a ) Ambient temperaturewithin the range of -40 (3 f0. m 300 I 000 not exceeding Altitude b) c) Frequencyof the a.c. power supply not lessthan 48 Hzand not exceeding62Hz d) Power-frequency voltage applied between the line and earth terminals of the arrester not exceedingits rated voltage. Arresters subjectedto other than normal application or serviceconditions may require special consideration in manufacture or application and each such case should be discussedwith the manufacturer. SeeAppendix B for abnormal serviceconditions and Appendix C, "Guide to the application of non-linear resistor type lightning arrestersfor a.c. systems".



SECTION TWO



DEFINITIONS



For the purposesof this Recommendation,the following definitionsare applicable. 3.



Lightning arrester (surge diverter) A device designedto protect electrical apparatus from high transient voltage and to limit the duration and frequently the amplitude of follow current. The term "lightning arrester" includes any external seriesgap which is essentialfor the proper functioning of the device as installedfor service,regardlessof whether or not it is supplied as an integral part of the device. Note. -



4.



Lightning arresters are usually connected between the electrical conductors of a network and earth although they may sometimes be connected across the windings of apparatus or between electrical conductors.



Non-Iinear resistor type (valve type) arrester An arrester having a single or a multiple spark-gapconnectedin serieswith one or more nonlinear resistors. Series gap of an arrester An intentional gap or gaps betweenspacedelectrodesin serieswith the non-linear seriesresistor or resistorsof the arrester.



6.



Non-linear seriesresistor of an arrester The part of the lightning arrester which, by its non-linear voltage-currentcharacteristics,acts as a low resistanceto the flow of high dischargecurrentsthus limiting the voltage acrossthe arrester terminals,and as a high resistanceat normal power-frequencyvoltage thus limiting the magnitude of follow current.



9 7.



Sectionof an arrester A cornplete, suitably housed part of an arrester including series gaps and non-linear series resistors in such a proportion as is necessaryto representthe behaviour of a complete arrester with respectto a particular test.



8.



Unit of an arrester A completely housed part of an arrester which may be connectedin serieswith other units to construct an arresterof higher voltage rating. A unit of an arresteris not necessarilya sectionof an arrester.



9.



Pressure-reliefdevice of an arrester A meansfor relievinginternal pressurein an arresterand preventingexplosiveshatteringof the housingfollowing prolonged passageof follow current or internal flashoverof the arrester.



10.



Rated voltage of an arrester The designatedmaximum permissibler.m.s. value of power-frequencyvoltage between its terminals at which it is designedto operatecorrectly. This voltage may be applied to the arrester continuouslywithout changingits operatingcharacteristics.



I l.



Rated frequencyof an arrester The frequency of the power systemon which the arresteris designedto be used.



12.



Disruptive discharge The phenomena associatedwith the failure of insulation under electric stress which include a collapseof voltage and the passageof current; the term appliesto electricalbreakdown in solid, liquid and gaseousdielectricsand combinationsof these. Note. -



13.



A ciisruptive discharge in a solid dielectric produces permanent loss of electric strengthl in a liquid or gaseous diclectric the loss may be only temporary.



Puncture(breakdown) A dis ru p ti v ed i s c h a rg eth ro u g h a s o l i d.



14.



Flashover A disruptivedischargeover a solid surface.



I 5.



Sparkoverof an arrester A disruptivedischargebetweenthe electrodesof the gaps of an arrester.



16.



Impulse A unidirectionalwave of voltageor current which, without appreciableoscillations.risesrapidly to a maximum value and falls, usually lessrapidly, to zero with small, if any, loops of opposite polarity. The parameterswhich definea voltage or current impulse are polarity, peak value, front time, and t im e to h a l f v a l u e o n th e ta i l .



17.



Rectangularimpulse A n im p u l s e w h i c h ri s e s ra p i d l y to a maxi munr val ue, remai ns substanti al l yconstant for a specifiedperiocl,and then falls rapidly to zero. The parameterswhich definea rectangularimpulseare polarity, peak value, virtual duration of the peak, and virtual total duration.



t:_



-



18.



ll -



Peak (crest) value of an impulse The maximum value of voltage or current in an impulse. In caseof superimposedoscillations, see Sub-clauses61.2, 63.2e) and 63.3.2c).



19.



Front of an impulse That part of an impulse which occurs prior to the peak.



20.



Tail of an impulse That part of an impulse which occurs after the peak.



21.



Full-wave voltage impulse A voltage impulse which is not interrupted by sparkover, flashover,or puncture.



22.



Choppedvoltage impulse A voltage impulse which is interrupted on the front, peak, or tail by sparkover, flashover or puncture causing a sudden drop in the voltage.



23.



Prospectivepeak (crest) value of a choppedvoltage impulse The peak (crest) value of the full-wave voltage impulse from which a chopped voltage impulse is derived.



24.



Virtual origin of an impulse The point on a graph of voltage vs. time or current vs. time determined by the intersection betweenthe time axis at zero voltage or zero current and a straight line drawn through two reference points on the front of the impulse. a) For voltage impulses with virtual front times equal to or less than 30 ps, the referencepoints shall be at 30 \ and 90\ of the peak value. b ) For voltage impulses with virtual front times greater than 30 ps, the origin is generally well defined and needsno artificial definition. c) For current impulses, the referencepoints shall be l0\ Note. -



25.



and 90"/" of the peak value.



This definitionappliesonly whenscalesof both ordinateand abscissa are linear. Seealso Note of Clause25.



Virtual front time of an impulse (Tr) The time, in microseconds,equal to: a) for voltage impulseswith front times equal to or lessthan 30 g.s,1.67times the time taken by the voltage to increasefrom 30/,to 90/" of its peak value; b ) for voltage impulses with front durations greater than 30 ps, 1.05 times the time taken bv the voltage to increasefrom zero to 95/" of its peak value; c) for current impulses, 1.25 times the time taken by the current to increasefrom l0/, to 90% of its peak value. Note. -



26.



If oscillationsare presenton the front, the referencepoints at l0l,30y;,90land on the mean curve drawn through the oscillations.



Virtual steepness of the front of an impulse The quotient of the peak value and the virtual front time of an impulse.



95){ shouldbe taken



13 --



27.



Virtual time to half value on the tail of an impulse (Tr) The time interval between the virtual origin and the instant when the voltage or current has decreasedto half its peak value. This time is expressedin microseconds.



18.



Waveshapedesignationof an impulse A combination of two numbers, the first representingthe virtual front time (fr) and the second the virtual time to half peak value on the tail (Tr), in microseconds. It is written as Ttf Tr, the sign "/" having no mathematicalmeaning.



29.



Standard lightning voltage impulse desi gnati onof 1.2/50. A r r im p u .l s ev o l ta g eh a v i n ga w a v e s h ape



30.



Switching voltage impulse An impulse voltage having a virtual front time greaterthan 30 ps,



31.



Virtual duration of the peak of a rectangular impulse The time during which the amplitude of the impulse is greaterthan 90\ of its peak value.



32.



Virtual total duration of a rectangular impulse The time during which the amplitude of the impulse is greater than l0/" of its peak value. If small oscillationsare presenton the front, a mean curve should be drawn in order to determinethe time at which the l0l. value is reached.



33.



Peak (crest) value of opposite polarity of an impulse The maximum amplitude of opposite polarity reachedby a voltage or current impulse when it oscillatesabout zero before attaining a permanent zero value.



34.



Discharge current of an arrester The surge or impulse current which flows through the arrester after a sparkover of the series gaps.



35.



Nominal dischargecurrent of an arrester The peak value of dischargecurrent, having an 8120waveshape,which is used to classify an arrester. It is also the discharsecurrent which is used to initiate follow current in the operating duty test.



36.



Follow current of an arrester The current from the connected power source which flows through an arrester following the passageof dischargecurrent.



37.



Residual voltage (dischargevoltage) of an arrester The voltage that appears between the terminals of an arrester during the passageof discharge current.



38.



Power-frequencysparkover voltage of an arrester The value of the power-frequencyvoltage measuredas the peak value divided by {f betweenthe terminals of an arrester,which causessparkover of all the seriesgaps.



applied



_ 1 5 _



19.



Impulse sparkover voltage of an arrester The highest value of voltage attained before sparkover during an impulse of given waveshape and polarity applied betweenthe terminals of an arrester.



.10.



Front-of-wave impulse sparkover voltage of an arrester The impulse sparkovervoltage obtained on the wavefront the voltage of which increaseslinearly with time.



41.



Standard lightning impulse sparkover voltage of an arrester The lowest prospectivepeak value of a standard lightning voltage impulse which, when applied to an arrester,causessparkover on every application.



42.



Time to sparkover of an arrester The time interval betweenvirtual origin and the instant of sparkover of, the arrester. The time is expressedin microseconds.



43.



Impulse sparkover-voltage/timecurve of an arrester A curve which relatesthe impulse sparkovervoltage to the time to sparkover.



44.



Prospective current The current which would flow at a given location in a circuit if it were short-circuited at that location by a link of negligibleimpedance.



45.



Type tests (design tests) Tests which are made upon the completion of the development of a new arrester design to establishrepresentativeperformance and to demonstratecompliance with this Recommendation. Once made, thesetests need not be repeatedunlessthe design is so changedas to modify its performance.



46.



Routine tests Tests made on each arrester or on parts and materials as required to ensure that the product rneetsthe design specifications.



47.



Acceptancetests Selectedtests which are made when it has been agreed betweenthe manufacturer and the purchaser that the arrestersor representativesamplesof an order are to be tested.



48.



Protective characteristics of an arrester The combination of the following: a) Lightning-voltage impulse sparkover-voltage/timecurve as determined in Sub-clause61.3. b) The residual-voltage/discharge-current curve as determined in Clause 62. c) For 10000 A arresters rated 100 kV and higher, the switching-voltage impulse sparkovervoltage/time curve as determined in Sub-clause61.4.



49.



Arrester disconnector A devicefor disconnectingan arresterfrom the systemin the event of arresterfailure to prevent a persistentfault on the systemand to give visible indication of the failed arrester. Note. -



Clearing of the fault current through the arrester during disconnection generally is not a function of the device, and it may not prevent explosive shattering of the housing following internal flashover of the arrester on high fault currents.



- 1 7 SECTION THREE 50.



IDENTIFICATION AND STANDARD RATINGS



Arresteridentification Lightning arrestersshall be identified by the following minimum information which shall appear o n the rating plate (nameplate): Rated voltage. Rated frequency, if other than one of the standard frequencies(Clause 52). Nominal dischargecurrent (specifying for the 5 000 A arrester whether SeriesA or SeriesB, and for the l0 000 A arrester, whether light or heavy duty). - Long-duration dischargeclass(for 10000 A heavy-duty arresters),seeSub-clause63.3.2. - Pressure-reliefclass(for arrestersfitted with pressure-reliefdevices),seeSub-clause65.2. - The manufacturer's name or trademark, type and identification. - The year of manufacture.



51.



Standard voltage ratings Standard values of rated voltage for arresters (in ki l ovol ts r.m.s.)shal l be: 0.175 0.280 0.500 0.660



7. 5 9 10.5 12



24 27 30 33



3



15



36



5l 54 60 75 84 96



39 2



t02 108



4.5 6



2



t8 1



4



120 126



r38 150 174 186 198



For voltage ratings above 198 kV, the arrester ratings should be determined as directed in Appendix C. The arrester ratings shall be divisible bv 6.



52.



Standard rated frequencies The standard rated frequenciesare 50 Hz and 60 Hz.



53.



Standard nominal dischargecurrents The standard nominal dischargecurrents are: 10 000 A, 5 000 A, 2 500 A and I 500 A, having an 8120waveshape. Note.- For the l0 000A arrester(seeClause54)therearetwo types,light-dutyandheavy-duty, whicharedifferentiated by the amplitude of the long-duration impulse current which they are capable of withstanding. See Sub-clause 63.3.



SECTION FOUR



54.



Arrester classification Lightning arrestersare classifiedby their standard nominal dischargecurrents and they shall meet at least the test requirements and performance characteristicslisted in Table I, page 19. Arresters having ntore favourable performance characteristicsor lower protective levels than are requiredin this Recommendationshall be consideredto have met this Recommendation.



SECTION FIVE



55.



ARRESTER CLASSIFICATION



GENERAL



TESTING PROCEDURE



Test samplesand measurements Except when specifiedotherwise,all tests shall be made on the same arresters,arrester sections or arrester units. They shall be new, clean, completely assembled,and arranged as nearly as possibleas in serviceand shall be fitted with grading rings, if used.



_ 1 9 _ The measuring equipment shall meet the requirements of I E C Publication 60 (1962), Highr oltage Test Techniques,and the values obtained shall be acceptedas accurate for the purpose of compliancewith the relevant test clauses. :6.



Power-frequencyvoltage tests All power-frequencytestsshall be nradewith an alternatingvoltagehaving a frequencybetween t lr e lim it s o f 4 8 H z a n d 6 2 H z , a n d a n approxi matel ysi nusoi dalw aveshape.



57.



Wet tests This clauseis in agreementwith the recommendationson wet testscontainedin I E C Publication 60 0962). It is generally recognized that wet tests are not intended to reproduce actual operating conditions but to provide a criterion based on accumulatedexperiencethat satisfactory serviceoperation will be obtained. Ta.srr | - Arrester classificqtionqnd test requirements Standard nonrinal discharee clrrrent A



l0 000r)



5 000 1)



L i g h t - d u t y I H e a v y - d L r t y S e r i c s A 2l)S e r i e s B 2 t (kV r.m.s.) 3 or more



l. Voltage 2. Power-frequency sparkover test



voltage



3. Standard lightning-voltage impulse sparkover test



4. Front-of-wave-voltaee sparkover test 5. Switching-voltage impulse sparkover-voltage/ time curve test



6. Residual voltage test



3 or more



3 through I



2 500



3 through 39



Up to 36



Up to 0.660



Clause60



Clar"rse 60



Clause60



Clause60



Clause60



Clause60



Sub-clause 61.2, Table VI, Colun-rn3



Sub-clause 61.2, Table VI, Colun-rn 3



Sub-clause 61.2, Table VI, Column 3



Sub-clause 61.2, Table VI, Column 5



Sub-clause 61.2, Table VI, Column 7



Not required



Sub-clause



Sub-clause 61.3.I



Sub-clause 6 1. 3 . 1



Sub-clause 6 1. 3 . 1



Sub-clause 61.3.1



Sub-clause 61.3.1



Sub-clause 6l.4 (above



Sub-clause 61.4 (above



Not required



Not required



100kv)



100kv)



Clause62, Table VII, Column 2



Clause62, Table VII, Colun-rn2



Clause62, TableVII, Colun-rn2



Clause62, Table VII, Colun-rn3



6l.3.r



Not required



Clause62, TableVlI, Coh"rmn4



Clause62, Table VII, Column 5



7. Current inrpulsewithstand: Sub-clauses Sub-clauses Sub-clauses Sub-clauses Sub-clauses Sub-clause a) High current



63.2



63.2



63.2



63.2



63.2



b) Longduration



63.3.3



63.3.2



63.3.3



63.3.3



63.3.3



Not required



Clause64



Clause64



8. Operating-dutytest



Clause64



Clause64



Clause64



Clause64



9. Pressure-relief test (when fitted with relief device)



Clar"rse 65



Clause65



Clause65



Clause65



Arrester disconnector (when fitted)



Clause66



Clause66



Clause66



Clause66



Not



Clause66



63.2



Not required



Clause66



t) In some countries, it is customary to classify arresters as: - station for 10000 A arresters; - intermediate (Series A) or distribution (Series B) for 5 000 A arresters; - secondary for I 500 A arresters. ')



Series A arresters are based on performance characteristics in practice in all countries. Series B arresters are based on performance characteristics in practice in Canada and the U.S.A. and other countries.



-2rThe test should give reproducible results in the same and in different laboratories. Wet tests shall be made only on arrestersdesignedfor use outdoors. Where such a test is specifled,the test object shall be subjectedto a spray of water of prescribedresistivity provided by a properly located nozzle or nozzles. The spray, consisting of small drops, shall fall on the test object at an angle approximately 45" to the vertical as determined by visual observation or by measurementsof the vertical and horizontal components of the precipitation rate. The vertical component of the spray shall be measuredwith a collecting vesselhaving a horizontal opening of area 100 cm2 to 750 cm2. When both vertical and horizontal components are required, the horizontal component will be measured with a collecting vesselhaving a similar vertical oper-ringdirected towards the nozzles. The collecting vesselshould be located on the side of the test object facing the nozzlesand as closeto the test object as is possiblewithout collecting splashesfrom it. For test objects of height greater than 50 cm, measurementsof the rate of precipitation shall be rnade near the ends and the middle and values obtained for any one position shall not differ by more than25\fuom the averagefor the three positions; for test objectsof 50 cm height or less, the measurementshall be made near the middle only. The test object shall be sprayedfor at least one minute before the application of voltage. (Alternatively, more consistent results may be obtained if the test object is thoroughly wetted with water of the prescribedresistivity and temperaturebefore the application of voltage.) The characteristicsof the spray shall be as given in the following table. Two setsare given, one in general accordancewith European practice,the other with practice in Canada and in the U.S.A. It is recommendedthat each National Committee use only one of thesepractices.



Tnsrn II Parameters for wet tests Characteristics Europe Precipitation rate vertical component



2. Resistivityof water



Canadaand U.S.A.



3 mm/min *



5 n r r n / m i n+ l 0 ? ;



l 0 0 0 0Q . c m + l 0 % Anrbient tenrperature



4. Type of nozzle



See



5. Water pressure



See Figure l x



1x