Disclosure to Promote the Right To Information

Whereas the Parliament of India has set out to provide a practical regime of right to information for citizens to secure access to information under the control of public authorities, in order to promote transparency and accountability in the working of every public authority, and whereas the attached publication of the Bureau of Indian Standards is of particular interest to the public, particularly disadvantaged communities and those engaged in the pursuit of education and knowledge, the attached public safety standard is made available to promote the timely dissemination of this information in an accurate manner to the public.

इंटरनेट मानक

“!ान $ एक न' भारत का +नम-ण”Satyanarayan Gangaram Pitroda

“Invent a New India Using Knowledge”

“प0रा1 को छोड न' 5 तरफ”Jawaharlal Nehru

“Step Out From the Old to the New”

“जान1 का अ+धकार, जी1 का अ+धकार”Mazdoor Kisan Shakti Sangathan

“The Right to Information, The Right to Live”

“!ान एक ऐसा खजाना > जो कभी च0राया नहB जा सकता है”Bhartṛhari—Nītiśatakam

“Knowledge is such a treasure which cannot be stolen”

“Invent a New India Using Knowledge”

है”ह”ह

IS 9000-2-1 to 4 (1977): Basic Environmental TestingProcedures for Electronic and Electrical Items, Part 2:Cold Test (Sections 1-4) [LITD 1: Environmental TestingProcedure]

Gr8

\ .,IS : 9000 ( Part II/Sec 1 to 4 ) - 1977

( R_fflnned 2004 )

Indian StandardBASIC ENVIRONMENTAL TESTING

PROCEDURES FOR ELECTRONICAND ELECTRICAL ITEMS

PART II COLD TEST

( Fourth Reprint APRIL 1997 )

UDC 621.38.038 : 620.192.422

o Copyright 1977

BUREAU OF INDIAN STANDARDSMANAK BHAVAN. 9 BAHADUR SHAH ZAFAR MARG

NEW DELHI 110002

December 1977

IS I 9000 ( Partn ) . 1977

Indian StandardBASIC ENVIRONMENTAL TESTING

PROCEDURES FOR ELECTRONICAND ELECfRICAL ITEMS

PART II COLD TEST

Environmental Testing Procedures Sectional Committee, LTOe 2

RI"llnJli",Instrumentation Ltd, Kota

CMi,_IIBIUO D. SWAltOOP

MI1IlHr1

5••1 H . R. BAPU SaETu.a.M Bharat EI~ctronics Ltd, BangaloreSHin p. S. K. Pa".D ( AU-U l

D. A. S. BHADUKI National Test House. CalcuttaSKat B. P. GIIOSR ( Alilmall l

BalO N. DAYAL Ministry of Defence (DGI)SKal G. R. GHOSR ( AI/I111411 )

DI.acwa ST.UfDAROS ( 5 &. T l Research, ~igns &. Standards Ora:anization( Ministry of Railways ), Lucknow

Posts and Te1erraphs Board, New DelhiPhilips India Limned, Bombay

SlIal J. G . JAtN

JOI~ DIJlBCTOR STAMn.'ROB( S &. T )-1 ( Altm,JJJI )

CIaIBRAL Sac'u:TARY Snciety of Environmental Engineers, BangaloreSIIJU T . C . S"I~IVAa"N ( AltlTftal. l

SRRI GHASITA SINGR Central Electronics Engineering Research Institute( CSIR l, Pilani

Radio Electronic &. Television Manufacturen'Association, Bomblay

CCHTRAL STAlfDARDIUTIOlfOnlcaR ( Allnrustl )

S""r JOHN FRANCISSICKI S. P, KULKA.Nr

D.P.K.D~.(AI~~)

S••r V. A. MoaAal Lucas-TVS LId, Mad....SRal B. K. BAIfBlUEs ( Azu.-tI )

SH"r D . V. PltTKAR Rhabha Atomic Research Centre, Trombay, Bomba)'SHar C. V. RAoRuRAMA::t National Radio &. Electronics Go Ltd, Bombay5... K . R••AN Directorate General of Observatories ( Ministry of

Tourism .t Civil Aviation ), New DeihiAll India Instrumen! Manufacturers' &. Dealers'

Auoc:iation, BombaySII1l1 H, C V •••• ( AIII'flllll )

Da Y. V. SoMATAlULU National Pbytical Laboratory ( CSIR ). New DelhiSRlll p. SUaYAlfAluT.• lf, ( AlInrt4l1 )

( Colllinwtl. P~r' 2 )

SRJlI P. SAIfDIl:LL

@ Co/J;Jritlrl 1977BUREAU OF INOlAN STANDARDS

This publication is protected under the l"tiiQ Co/,pi,JiI Ad (XIV of 1957) andreproduction in whole or in part by any m~aas except with wr itten permission of thepublisher Ihall be deemed to be an infringement of copyright under the said Act.

1819000 (Part d)-I977

( CMti_dfto. ,." I )

M"'*rr ~I

Smu T. V. A. SUBaAllAXUlf Electronia Corporatioo of India Ltd, HyderabadSJtRl G. C. SAIZlfA ( AlImt4U )

SIIlU D. SUBBAJLUIYAN Indian Telephone IndUlt.riea Ltd, BanplorcSJlal A. SATBYAlfAJUT..IJIA ( AluntaI.)

SBBI K. N. TIWARI MiDiatry of Defenee ( R a: D )SJlBI P. K. SHUKLA ( Altn'll4t6 )

SBBI N. SaIN",AlAI(, Director General, lSI ( Ex-o.ffkio M,tIlHr)DireclOr ( Eleetronia ) ( SlC'fItcv )

2

IS • 9000 ( Pal't U ) • 1917

Indian StandardBASIC ENVIRONMENTAL TESTINGPROCEDURES FOR ELECTRONIC

AND ELECTRICAL ITEMS

PART II COLD TEST

o. FOR E W 0 R D

0.1 This Indian Standard (Part II) was adopted by the Indian StandardsInstitution on 7 June 1977, after the draft finalized by the Envir.-:>nmentalTesting Procedures Sectional Committee had been approved by theElectronics and Telecommunication Division Council.

0.2 The differences in environmental testing procedures for componenttype items and equipment type items are fast disappearing in the contextof technological developments. It is, therefore, felt necessary to paveuniform testing procedures wherever possible. This series of standard.on environmental testing procedures (IS: 9000) has been prepared withthis objective. This is also in line with the principle adopted byIECrrC 50 I Environmental Testing' in developing unified series ofstandards on environmental testing procedures by International Electro­technical Commission.

0.2.1 It is proposed to withdraw the existing Indian Standards, namely.IS: 589-1961* and IS: 2106t series dealing with environmental tests forelectronic components and equipment respectively, as soon as the testsmentioned therein are covered in the new series ( IS: 9000 ).

0.3 This standard deals with cold tests applicable both to non-heatdissipating and heat dissipating items.

0.01 The object of the cold test is limited to the determination of theability of components, equipment or other articles to be used o- stored atlow temperature. These cold tests do not enable the ability of item. towithstand or operate during temperature variations to be assessed.In this case, it would be necessary to usc I change of temperature test'[SII IS: 9000 ( Part XIV) - 1978 t l-

-Basic climalic and mt'chanical durabiliay teaU for compcmenu fOl' electronic anddecuir.a} equipment ( rniwl).

>Environmental lesl5 for el~clronic and c1t'Ctrical equipment,tBasic environmental lestil1!{ procedures for cleetronie and eleerrieal items: Part XIV

Change of temperalur..

3

15 I 9000 ( Part n )·1977

0.5 This standard is based on IEC Publication 68-2-1 (1974) • Basicenvironmental testing procedures, Part 2: Tests, Tests A: Cold' issued bythe International Electrotechnical Commission.

0.6 In reporting the result of a test made in accordance with thisstandard, if the final value, observed or calculated, is to be rounded off,it shall be done in accordance with IS: 2-1960-.

-Rules for rounding oIfaumeric:d values ( rmml).

c)d)

IS I 9000 ( Part Dj8ec 1 ) - 1917

Indian StandardBASIC ENVIRONMENTAL TESTINGPROCEDURES FOR ELECTRONIC

AND ELECTRICAL ITEMS

PART II COLD TEST

Section General

1. SCOPE

1.1 This standard ( Part II/Sec I ) gives general information on coldtests applicable both to non-heat dissipating and heat dissipating items.

2. TERMINOLOGY2.1 For the purpose of this standard, the definitions and explanation ofterms given in IS: 9000 (Part I )-1977* shall apply.

3. CLASSIFICATION OF COLD TESTS

3.1 The cold tests are classified as follows ( see also Table 1 ):a) Cold tests for non-heat dissipating item:

1) With sudden change of temperature ( see Sec 2 ),2) With gradual change of temperature ( see Sec 3 ),

b) Cold tests for heat dissipating items:1) With gradual change of temperature (see Sec 4).

TABLE 1 CLASSlnCATION OF COLD TESTS

S",.,.,x Lw:TTl':1L ITEK TypE TEIIl'EJlAT'-'RlC tIT-II TE)IPP:RATI'IlP: AT

(&, 7 ~IfD CHANGE Cn_EXCEM F.NT OF

FIOII. I AND 2 ) TEST DUKATION

a) Non·heat Sudden Stabilizeddissiptuing (JII Note)

b) Non-heat Gradual StabilizeddissipatiDI (JII Note)

Heat Gradual Stabilizeddissipating (rt. Note)

NOTE - The itenu will normally reach temperature stability before cornmencernemof test duration. In exceptional cases, this will not be so, and additional informationmay be required to be specified in the relevant individual standard.

-Basic environmental testing procedures for electronic and electrical items: Part IGenerat ,

5

IS. lOGO ( Part D/8ec 1 ) • 1t77

-t. APPLICATION OF COLD TESTS

4.1 G...ral- The procedures given in thil standard are normallyintended for items which achieve temperature stability during theperformance of the test procedure. The duration of the test commencesat the time when temperature stability of the item has been reached. Forthe exceptional casea when the item does not reach temperature stabilityduring the performance of the test procedure, the duration of the testcommences at the time when the test chamber reaches the testtemperature.

4.1.1 The relevant spec ification shall define:a) the rate of change of temperature in the test chamber,b) the time at wh ich the items are introduced into the test

chamber,c) the time at which the exposure commences, andd) the time at which the items are energized.

Nonl - Guidance on choo.ing the four paramet~ menrioned in 4.1.1 are given inIS: 9001 ( Part n )-1977-.

4.2 For Heat DI.8ipadaS Item. - An item is considered heatd iuipating only if the hottest point on its surface, measured in free airconditions (that is, with no forced air circulation) is more than 5°Cabove the ambient temperature of the surrounding atmosphere aftertemperature stability has been reached [ Stt 2.1.3 of IS: 9000 (Part 1)­1977t]. In such cases the cold tests specified in Section'" shall apply.

4.2.1 For such items, when the relevant specification calls for a storagetest or does not specify an applied load during the test, the cold testspecified in Section 3 shall apply.

4.3 For NOlI-Heat DI••lpadaS Itaa.

4.3.1 In cold test for .non-heat dissipatin~ it~mswith sudden change oftemperature (SII Section 2), the Item IS introduced into the testchamber, the latter being at the temperature specified for the test. Ithas been introduced as a convenient and time-saving method, This testshall be used only where it u known that the effects of a sudden changeof temperature are not detrimental to the test item.

4.3.2 In cold test for non-heat dwipating items with gradual change oftemperature ( Itt Section 3 ), the item is introduced into the test chamber,the latter being at the laboratory temperature. The temperature in thechamber is then reduced gradually so as to cause no detrimental dfect.on the test item due to the temperature change.

-G\lidance for environmental latina: Pan II Cold aDd dry heat testl

tBuic mYirOllJDmtal testing peeeedures for electronic and electrical heme: Part IGeneral.

6

IS : 9000 ( Part II/Sec 1 ) • 1977

4.3.3 Where it is not possible to introduce the item into a cold chamberwithout frost problems, either because of its size ?r because of complexfunctional test connections, then cold test with gradual change oftemperature (It' Section 3 ) shall be used.

S. GUIDANCE ON COLD TESTS

5.1 The guidance details for the diffl rent types of cold tests are givenin IS: 9001 (Part II )-1977· which is a necessary adjunct to thissrandard.

6. TESTING OF HEAT DISSIPATING ITEMS WITH ANDWITHOUT FORCED AIR CIRCULATION

6.1 The preferable method of testing heat dissipating items is thatwhich docs not use forced air circulation.

6.2 If this is impracticable, cold test with forced air circulation, thedetails of which are covered in Section 4, may be applied.

6.2.1 Two methods fo>r testing with air circulation are given (MethodA and Method B). Method A applies to the cases where the chamber islarge enough tu comply with the requirements for testing without forcedair Circulation, but where it is not possible to maintain the lowtemperature without circulating the air in the chamber. Method Bapplies to the cases where the chamber is too small to comply with therequ irements for testing without forced air circulation.

7. DIAGRAMMATIC REPRESENTATIONS

7.1 To facilitate the choice of test method, a diagrammatic representa­tion of the various procedures is given in Fig. I. Several clauses areidentical, especially in Section 2 and Section 3. A block diagramshowing which clauses are identical and which are different is givenin Fig. 2.

·GuidaDcc for envinmmmtal testing: Pan n Cold aDd dry heat tests

7

18 r9000 ( Part II/Sec I ) • 1977

ITEM WITHARTIFICIALCOOLING

COOLING SYSTEMNOT ISOLATEDFROM THECHAMBER

COOLING SySTEMISOLATED FROMTHE CHAMBER

ITEM WITHOUTARTIFICIALCOOLING

TESTING WITHFORCED AIRCIRCULATION

TESTING WITHNO FORCED AICIRCULATION

WITH GRADUALCHANGE OF

TEMPERATURE~ ~~~~c;~~~ ~

FOR NON-HEATDISSIPATING

ITEM

WITH SUDDENCHANGE OFTEMPERAfURE

Fro. I DIAOIlAJoOIATIC REPRESENTATION OP TilE VARIOUS

TEST PaOCKDURItS

8

11,_(Partll/leel)-Im.. . ~

a ... a ... a ......._ ~. -'fitOw 0 ... 0111(J ... U'" U ...

a • b • dlatr0ducti08

DacripcioD or Tat AppualUa

Object

As in the Original Standard, this Page is Intentionally Left Blank

18 • 9000 ( Part D/Sec 2 ) - 1977

Indian StandardBASIC ENVIRONMENTAL TESTING

PROCEDURES FOR ELECTRONICAND ELECTRICAL ITEMS

PART II COLD TEST

Section 1 Cold Test for Non-Heat Dlnlpatlnl Items withSudden Chan.. of Temperature

I. SCOPE

1.1 This standard ( Part II/Sec 2) deals with cold test for non-heatdissipating items with sudden change of temperature.

2. TERMINOLOGY

2.1 For the purpose of this standard, the definitions and explanation ofterms given in IS: 9000 ( Part I ).1977- shall apply.

So OBJECT

3.1 The object of this standard is to provide test procedure to determinethe suitability of non-heat dissipating items for use and/or storage underconditions of low temperature and for which the subjection to a suddenchange of temperature has no detrimental effects.

3.1.1 This procedure is for items which are subjected to . a lowtemperature for a t ime long enough for the item to achieve temperaturestability.

3.1.2 In th is procedure, the test duration is normally measured fromthe time when the item achieves temperature stability. For cases wherethis does not apply, Sit f.1 of Secion I.

f. GENERAL DESC1UPl10Nf.l In this test, the item while being at the ambient temperature oC thelaboratory is introduced into the chamber, the latter being at thetemperature appropriate to the degree of severity as specified in therelevant specification. After temperature stability of the test item hasbeen reached, the item is exposed to these conditions for the specifiedduration. Items under test are normally in non-operating conditions.

• Basic CDvirolunenlal testing procedures for elec:troo.ic and electrical item&: Part IGeneral.

II

II, toGO ( Part II/Sec 2 ). 1'77

4.2 Forced air circulation is normally used for this test,

5. DESCIUPTION OF TEST APPARATUS

5.1 The chamber shall conform to relevant provrsrons of IS : 9002(Part I )-1977- as applicable fur carrying out cold test on non-heatdissipating items with sudden change of temperature, The sign ificantrequirements are briefly described in 5.1.1 and 5.1.2.

5.1.1 The chamber shall be capable of maintaining the specifiedtemperature in the working space within the tolerances given in 6.I (a).Forced a ir circulation may be used to maintain homogeneous conditions.

5.1.2 In order to limit radiation problems, the temperature of thewalls of the chamber shall not differ by more than 8 percent of thespecified ambient temperature of the test, expressed in K . This require­ment applies to all parts of the chamber walls and the items shall heunable to 'see' any heating or cooling elements which do not complywith this requirement.

6. SEVEIUTIEI6.1 The severities, as indicated by temperature and duration of exposure,shall be specified in the relevant specification. The values shall beselected from those given below:

a) Temperalu.re:-65 :I: s-c-55 :I: 3°e-40 :I: 3°e-25 :I: 3°e-10 :I: 3°e+5 :I: s-c

b) DurIJ'ulII:2 hours4 hours

16 hours72 hours96 hours

6.2 Where this testing procedure is used in connection with test'associated with endurance or reliability, due note shall be taken ofrelevant standards which give particular requirements for durations forsuch tests.

-Equipment fOl' environmental testa for electronic and electrical itenu: Pan I Chamber_cold tell.

12

IS I 9000 ( Part II/Sec 2 ) • 1977

6.3 If the only intention of the testing procedure is to show whether theitem will function at low temperature, the conditioning may be limitedto a time such that the item under test has reached temperature stability.In no case shall the duration be less than 30 minutes.

7. PRECOND~O~G7.1 The relevant specification may call for a preconditioning.

I. INITIAL MEASUREMENTS

1.1 The item shall be visually inspected and electrically and mechani­cally checked as required by the relevant specification.

9. CONOmONING9.1 The chamber shall be at the temperature of the specified severity.The item, while being at the ambient temperature of the laboratory,shall be introduced into the chamber in the unpacked, switched off' readyfor use' state, in its normal position, or as otherwise specified.

9.1.1 When the test item is intended for use with specific mountingdevices, these should be used for testing.

~.1.2 The test (ambient) temperature shall be measured as in 2.1 of15:9000 ( Part I ).1977*.9.2 Time shall then be allowed for the chamber conditions to bere-established and for the item to reach temperature stability.

9.3 If required by the relevant specification, the item shall be switched onor electrically loaded and checked to ascertain whether it is capable offunctioning in accordance with the relevant specification.

9.3.1 If required by the relevant specification, the item shall remainin operating condition in accordance with the duty cycle and at theloading condition ( if applicable) as prescribed by the relevant speci­fication, or be switched off.

NOTS- An item. even under operating or loaded conditions shall be considered asnon-h~at diJIipating as lo~ as itl lurface temperature rise is not more than SoC abovethe ambicut temperature.

9.4 The item shall then be exposed to the low temperature conditions fora duration as specified in the relevant specification.

9.f.1 The duration shall be measured from the time when temperaturestability has been reached.

NOTa - In the case of small ltems, it is Dot necessary to check by measurementthat temperature stabil ity has been reached [I. Note 2 of2.S orIS: 9000 (Part I )_19770

].

*Basic cuvironmental testing procedures for eleetrealc and electrical items: Part IGeneraJ.

13

18a9000 ( Part U/Sec 2 ) • 1m9.5 If requ ired by the relevant specification, intermediate measurementsshall be performed in accordance with 10.

9.6 At the end of this period, the item shall be subjected ru th e recoveryprocedure. I II case the item remains in o pc rnt ing or loaded condit ionsduring the test , it shall be switched off fir unloaded before beingsuhjected to the rec overy procedure.

10. INTERMEDIATE MEASUREMENTS

10.1 The relevant sper ificat ion may cal l for loadin~ ancl/or measure­ments during' or at the e-nd of conditi oning whih- t lu- item is still in thech amber. If such measurrments are rvqu ired , tlu- rr k-vnnt specifi car ionshall define th e measu rements a nd t he per iod o r [)I'riods after whi ch tlwvshall be carr it'd out. For these measurements, the ite m shall n ut beremoved from the ch amber.

NOTB - M~asur..m en" preceded hy r..co v..ry. wh ich would require removal a ndreintroduction of Ih e ilems into the cha m be r, ar e not perruissible during rheconditioning.

If it is desired to Icnow rhe performance of the rvpes of it em before Ill.. ..nd of theprescribed d ura t jon. on e addir iona! 101 will be , equired for each spt'cili~tl dural ion.Recovery and final measurements shall be performed separal ..ly for ..ach lot.

11. RECOVERY

11.1 The item shall remain under standard recovery conditions untildefrosted.

11.2 To remove droplets of water, the item may be shaken by hand or ablast of air at laboratory temperature may be applied for a short time.

11.3 The item shall then remain under recovery cond it ions for a perjodadequate for the attainment of temperature stability with a minimum of1 hour.

11.3.1 When several items are tested simultaneously and where theI hour recovery period is inadequate, the maximum period for recoveryshall be 2 hours and alI measurements shall be completed at the end ofthis period.

11.f If required by the relevan~ specificatio~, the item shall be switchedon 01· loaded and measured contmuously during the recovery period.

11.5 If the recovery conditions given are not appropriate for the itemto be tested, the relevant specification may call for other recoveryconditions.

18 I .. ( Part D/See 2 ) - 1977

12. PINAL MEASUREMENTS

12.1 The item shall be vilUally inspected and electrically and mechani­cally checked as required by the relevant specification.

13. INPORMATION TO BE GIVEN IN THE RELEVANTSPECIFICATION

13.1 When thil test il included in the relevant specification, the followingdetails IbaH be given as far as they are applicable:

a) Preconditioning;b) Initial measurements;c) State of item during conditioning;d) Severity ( temperature and duration of exposure );e) Intermediate measurements;f) Recovery, if non-standard;g) Final measurements; andh) Any deviation in procedure as agreed upon between the purchaser

and the manufa..:turer.

IS

.-

IS I 9000 ( Part D/See 3 ) • 1m

Indian StandardBASIC ENVIRONMENTAL TESTINGPROCEDURES FOR ELECTRONIC

AND ELECTRICAL ITEMS

PART II COLD TEST

Section 1 Cold Test for Non-Heat Dissipatin, Itein. withGradual Chan,e of Temperature

1. SCOPEl.t This standard (Part II/Sec 3) deals with cold test for non-heatdissipating items with gradual change of temperature.

2. TERMINOLOGY2.1 For the purpose of this standard, the definitions and explanation ofterms given in IS: 9000 ( Part I )-1977· shall apply.

3. OBJECT3.1 The object of this standard is to provide a test procedure todetermine the suitability of non-heat dissipating items for use and/orstorage under conditions of low temperature.

3.1.1 The procedure is for items which are subjected to a lowtemperature for a time long enough for the item to achieve temperaturestability.

3.1.2 In th is procedure, the test duration is normally measured fromthe t ime when the item achieves temperature stability. For cases wherethis does not apply, se«4.1 of Section l ,

4. GENERAL DESCRIPTION4.1 In this test , the item while being at the ambient temperature of thelaboratory is introduced into the chamber, the latter being at thetemperature of the laboratory. The. temperature is then graduallyreduced to the temperatur~ approprIate to the degree of severity asspecified in the relevant speclfic~ltlOn: After temperature stability of thetest item has been reached, the Item 15 exposed to these conditions for thespecified duration. Items under test are normally in non-operatingconditions.

e8a5ic environmmlal lot ing procedures for electronic aDd electrical items: Pan IGeneral .

17

IS I 9000 ( Part II/Sec 3 ) • 1977

4.2 Forced air circulation is normally used fur this test.

S. DESCRIPTION OF TEST APPARATUS

5.1 The chamber shal1 conform to the relevant provisions of IS :9002(Part ( )-1977· as applicable for carrying out cold test on non-heatdissipating items with gradual change of temperature. The significantrequirements are briefly descs ibed in 5.1.1 and 5.1.2.

5.1.1 The chamber shall be capable of maintaining the spec ifiedtemperature in the working space within til e tolerances given in 6.1(a).Forced air circulation may be used to maintain homogeneous conditions.

5.1.2 In order to limit radiation problems, the temperature of the wAilsof the chamber, after temperature stability has been reached , shall notdiffer by more than 8 percent of the specified ambient temperature of thetest, expressed jin K . This requirement applies to al1 pa rts of thechamber walls and the items shall be unable to •see' any heating orcooling elements which do not comply with this requirement.

6. SEVERITIES

6.1 The severities, as indicated by temperature and duration of exposure,shall be specified in the relevant specification. The values shall beselected from those given below:

a) Tempera/UTe:-65 :C 3°e-55 :i: 3°e-40 :i: 3°C-25 :i: 3-C-10:i: 3°C+5 :i: 3-C

b) Duration:

2 hours4 hours

16 hours72 hours96 hours

6.2 Where this testing procedure is used in connection with testsassociated with endurance or reliability, due note shal1 be taken ofrelevant standards which give particular requirements for duration forsuch tests.

-Equipment for environmeDtal t~t. for elee rronie and eleetrica; item.: Part IChamber for cold test,

18

18 1 9000 ( Part "{Sec' ) -1977

6.3 If the only intention of the testing procedur~ .is t? show wheth~r .theitem shall function at low temperature, the conditioning may be h~l.tedto a time such that the item under test has reached temperature stability,I n no case shall the duration be less than 30 minutes.

7. PRECONDITIONING

7.1 The relevant specification may call for a preconditioning.

8. INITIAL MEASUREMENTS

8.1 The item shall be visually inspected and electrically and mechani­cally checked as required by the relevant specification.

9. CONDITIONING

9.1 The chamber shall be at the temperature of the laboratory.

9.1.1 The item, while being at the ambient temperature of thelaboratory, shall be introduced in to the chamber in the unpacked,switched off, • ready for use' state, in its normal position or as otherwisespecified.

9.1.2 When the (est item is intended for use with specific mountingdevices, these should be used fur testing.

9.2 The temperature within the chamber shall then be gradually reducedto th e temperature appropriate to the degree of severity and time shallbe allowed for the item to reach temperature stability.

9.2.1 The rate of change of temperature within the chamber shall notexceed 1°C per minute, averaged over a period of not morethan 5 m inutes.

9.2.2 The test (ambient) temperature shall be measured as in 2.1 ofIS: 9000 ( Part 1).1977·.

9.3 The item shall be switched on or electrically loaded and checked toascertain whether it is capable of functioning in accordance with therelevant specification.

9.3.1 If required by the relevant specification, the item shall remain inoperating condition in accordance with the duty cycle and at the loadingcondition (if applicable} as prescribed by the relevant specification, or beswitched off.

N~ - An item, even under operating or loaded eonditions shall be considered asnon-hat dissipatin« as long as iu IUrface temperature rise is not more than SoC abovethe ambient temperature.

-Basic env ironmental tesling pI'OCedures for electronic and electrical items: Part IGeneral.

]9

IS : 9000 ( Part U/Sec 3 ) • 1977

9.4 The item shall then be exposed to the low temperature conditions fora duration as specified in the relevant specification.

9.f.l The duration shall be measured from the time when temperaturestability has been reached.

N~ - In the case of small items. it i. not necessary to check by meUUrTmentthat telnperature stabillry has been reached [ III Note 2 of 2.3 of IS : 9000 ( Pan I ).1977- ].

9.5 If required by the relevant specification, intermediate measurementsshall be performed in accordance with 10.

9.6 At the end of this period, the item shall remain in the chamber andthe temperature shall be gradually raised to a value lying within thelimits of standard atmospheric conditions for testing.

9.6.1 The rate of change of temperature within the chamber shall notexceed 1°C per minute, averaged over a period of not more than5 m inutes.

9.6.'l At the end of this per iod, the item shall be subjected to therecovery procedure in the chamber or otherwise as appropriate.

9.6.3 In case the item remains in operating or loaded conditions duringthe test, it shall be switched off or unloaded before the temperature israised.

10. INTERMEDIATE MEASUREMENTS

10.1 The relevant specification may call for loading and/or measurementsduring or at the end of conditioning while the item is still in the chamber.If such measurements are required, the relevant specification shalldefine the measurements and the period or periods after which they shallbe carried out. For these measurements, the item shall nut be removedfrom the chamber.

NOTB - Measurements preceded by recovery. which would rt'quire removal andreintroduction of the items into the chamber, are nol ptrmlllib/e durin, theconditioning.

Ifit is desired to know the performance of the type of item before Ihe end of theprescribed duration, one additional lot will be required for each specified duration.Recovery and final measurements shall be performed separately for each 101.

11. RECOVERY11.1 To remove droplets of water, the item may be shak;.n by hand or ablast of air at laboratory temperature may be applied for a shortduration.

_Basic environmental testing procedures for electronic and electrical ilellll: Part IGeneral.

20

IS. 9000 ( Part DfSec :J )-1m11.2 The item shal] then remain under standard recovery conditions fora period adequate for the attainment of temperature stability, with aminimum of 1 hour.

11.2.1 Whl':n several items are tested simultaneously and where theI hour recovery period is ir vdequate, the maximum period for recoveryshall be 2 hours and all measurements shal] be completed at the end ofth is period.

11.3 If required by the relevant specification, the item shall be switchedon or loaded and measured continuously during the recovery period.

11.4 If the recovery conditions given are not appropriate for the itemto be tested, the relevant specification may call for other recoveryconditions.

12. FINAL MEASUREMENTS

J2.1 The item shall be visually inspected and electrically and mechani­cally checked as required by the relevant specification.

111NFORMATJON TO BE GIVEN IN THB RELEVANTSr·EClnCATION

111 When this test i~ included in the relevant specification, the followingdetails shall be given as far as they are applicable:

a) Preconditioning;b) Initial measurements;c) State of item during conditioning;d) Severity (temperature and duration of exposure);e) I ntermediate measurements;f) Recovery, if non-standard;g) Final measurement'; andh) Any deviation in procedure as agreed upon between the purchaaer

and the rnariufacturer.

21

ISr9lOO (Part II/Sec f) ·1977

Indian StandardBASIC ENVIRONMENTAL TESTINGPROCEDURES FOR ELECTRONIC

AND ELECTRICAL ITEMSPART II COLD TEST

Section" Cold Test for Heat Dlulpatin. Item. withGradual Chan.. of Temperature

1. SCOPE

1.1 19is standard (Part II/Sec 4) deals with cold test for heatdissipating items with gradual change of temperature.

2. TERMINOLOGY

2.1 For the purpose ot this standard, the definitions and explanation ofterms given in IS : 9000 ( Part I )-1977- shall apply.

3. OBJECT

3.1 The object of this standard is to provide a test procedure todetermine the suitability of heat dissipating items for use under conditionsof low temperature.

3.1.1 This 'procedure is for items which are subjected to a lowtemperature for a time long enough Cor the item to achieve temperaturestability.

3.1.2 In this procedure, the test duration is normally measured fromthe time when the item achieves temperature stability. For cases wherethis does not apply, se« 3.1 of Section 1.

4. GENERAL DESClUPTION

4.1 In this test, the item while being at the ambient temperature of thelaboratory is introduced into the . chamber, the latter being at thetemperature of the laboratory. Th-: temperature is then graduallyreduced to the temperature appropriate to the degree oC severity asspecified in the relevant specification.

~c environmental tettin, procedures for dcctJ'oDic aDd dcetric:aJ items: Part I

23

IS I 9000 ( Part D/Sec: f ) • 1977

. 4.1:1 After temperature stability of the test item haa been reached theItem IS exposed to these conditions for the specified duration.

. "'1..2 The relevant specification shall define the functioning of theItem under test.

...1.3 Care .sha ll be takc:n ~hat. any cooling devices of the item are inaccordance with the prescrrption ID the relevant specification.

~1.f:I'he test conditions are designed to simulate the effects ofsubjecting the test items to 'free air" conditions with defined thermalconduction characteristics of the mounting.

f.2 The specified test temperature is defined as the ambient temperature.

f.3 Testing with no forced air circulation is the preferred method.Forced air circulation may. however. be used when it is difficult orimpossible to meet the conditions specified for testing without aircirculation.

5. DESCRIPTION OF TEST APPARATUS

5.1 TestiDg Chamber - The chamber shall conform to relevantprovisions of IS : 9002 (Part I )-1977· as applicable for carrying out coldtest on heat dissipating items with gradual change of temperature. Thesignificant requirements are briefly described in 5.1.1 to 5.1.5.

5.1.1 The temperature in the chamber shall bechecked by temperaturesensing devices located so as to comply with the requirements of 2.1.2of IS : 9000 ( Part I )-1977t.

5.1.2 In the case of testing with no forced air circulation. the chambershall be large .enough compared with the size and amount of heatdissipation of the test item to allow a simulation of the effects of C freeair' conditions.

This requirement is assumed to be met if the minimum distancebetween any surface of the test item and .the corresponding wall of thechamber is not less than 15 em and the ratio between the volume of thechamber and the volume of the item is not less than 5: I. The itemshould as far as practical be placed close to the centre of the testchamber so as to have as much space as possible between any part of thetest item and the chamber walls.

*Equipment for enYiroamental testl foc electronic and electrical items: Pan JChamber tor cold test. . ' .

tBasic environmental tcstiDg procedurcll tor e1ectroDlC and electrical Itema: Part I. Grneral.

24

IS I 9000 ( Part II/Sec .. ) • 1977

5.1.3 In order to limit radiation problems, the temperature of thewalls of the chamber, after temperature stability has been reached, shallnot differ by more than 8 percent of the specified ambient temperatureof the test, expressed in K . This requirement applies to all parts of thechamber walls and the items shall be unable to 'see' any heating 01

cooling elements which do not comply with this requirement.

5.t.4 In the case of testing in a chamber with forced air circulation,the v-Iocity of the air should be as low as possible.

5.1.5 Where a duty cycle is specified, precautions have to be taken ifthe test temperature is to be maintained at a steady figure.

In the case of components, a staggering of the on-periods willusually suffice, provided that at any time the distribution of componentsun-load is reasonably unifurm throughout the test chamber.

5.2 MOUDtiDI

5.2.1 The thermal conduction and other relevant characteristics of themounting and connections of the test item should be specified in therelevant specification. When the test item is intended for use withspecific mounting devices, these shall be used for testing.

5.2.2 Where nothing is known about the mounting characteristics, thethermal conduction of the mounting shall be high.

6. SEVERITIES

6.1 The severities, as indicated by temperature and duration ofexposure,shall be specified in the relevant specification. The values shall beselected from those given below:

a) T'emperatur«:

-65 :i: 3°C-55 :i: goC-40 :i: 3~C

-25 :I: goC-10 :i: 3~C

+5 :!: 3°C

b) Duration:

2 hours4 hours

16 hours72 hours96 hours

25

IS I 9000 ( Part D/sec f ) • 1917

6.2 Where this testing procedure is used in connection with testsassociated with endurance or reliability, due Dote shall be taken ofrelevant standards which give particular requirement for duration forsuch tests. .

6.3 If the only intention of the testing procedure is to show whether theitem will function at low temperature, the conditioning may be limitedto a time such that the item under test has reached temperature stability.In no case shalI the duration be less than 30 minutes.

7. PRECONDITIONING

7.1 The relevant specification may call for a preconditioning.

8. INITIAL MEASUREMENTS

Ll The item shall be visually inspected and electrically and mechani·cally checked as required by the relevant specification.

9. CONDITIONING

9.1 Item. Without Artificial Coou..9.1.1 Tutin, With No Forced Air Circwlation

9.1.1.1 The chamber shall be at the temperature of the laboratory.

The item, while being at the ambient temperature of the laboratory,shall be introduced into the chamber in the unpacked, switched off• ready for~' state, in its normal position or u otherwise specified.

9.1.1.2 The temperature within the chamber shall then be graduallyreduced to the temperature appropriate to the degree of severity andtime shall be allowCd for the item to reach temperature stability.

The rate of change of temperature within the chamber shaU notexceed 100 per miDute, averaged over a period of not more than.5minutes.

'.1.1.3 The item shall be switched on or electrically loaded andchecked to ascertain whether it is capable of functioning in accordancewith the relevant specification.

The item shall remain in the operating condition in accordance withthe duty cycle and at the loading condition (if applicable) as prescribedby the relevant specification.

26

IS : 9000 ( Part II/Sec 4 ) -1977

9.1.1.4 The item shall then be exposed to the low temperatureconditions for a duration as specified in the relevant specifi cat ion. Theduration shall be measured from the time when temperature stabil ity hasbeen reached.

:-JOT!: - In the case of small items, it is not necessary to check by measurement thattemperature stabi lity has been reached [se. Note 2 or 2.1 or IS : 9000 (Part I )­1977- 1.

9.1.1.5 If required by the relevant specification, intermediatemeasurements shall be performed in accordance with 10.

9.1.1 .6 At th e end of this per iod, the item shall remain in thechamber and the temperature shall be gradually raised to a value lyingwithin the limits of standard atmospheric conditions for testing. Therate of change of the temperature within the chamber shall not exceed1°C per minute, averaged over a period of not more than 5 minutes.

In case the item remains in operating or loaded conditions duringthe test, it shall be switched off or unloaded before the temperature israised .

9.1.1.7 At the end of this period, the item shall be subjected to therecovery procedure in the chamber or otherwise as appropriate.

9.1.2 Tlsting With Forced Ai, Ci,culation

9.1.2.0 Either of the methods described in 9.I:Z.l and 9.1.2.2 whereforced air circulation is allowed, may be used when it is not possible tomeet the conditions specified for testing without air circulation.

9.1.'l.1 Mtthod A - This method is intended to be used when thechamber used for the testing is large enough to comply with therequirements for testing without forced air circulation but maintenanceof the ambient temperature in the chamber can only be obtained bycirculation of air.

The item is placed or assembled inside the test chamber. With boththe chamb~rair fio~.and cool.ing switched off, the item shall be subjectedto the loading conditions specified for the low temperature at .which thetest is to be carried out.

When temperature stability of the item has been reached, thetemperature of a number of representative points shall be measuredusin@' a suitable monitoring device. The temperature rise which occursat each point shan then be noted.

-Basic environmental Jesting procedures ror electronic and electrical itellll: Part IGeneral.

27

IS z toGO ( Part D/See f ) • 1977

The chamber air flow u switched on and, once temperature stabilityhas been achieved, the temperature of the representative points shallagain be measured. If the temperatures differ from those measuredwithout air flow by more than 3°C or any other value stated by therelevant specification, the velocity of the air is too high and shall bereduced until the requirement of 3°C or other specified temperaturedifference is met. If this is not possible, Method B shall be used.

The chamber cooling is now switched on for the commencement oftest ing. The measuring of ambient temperature shall be carried out inaccorda nce with 2.1.2 of IS : 9000 ( Part I )-1977·.

T esting shall proceed in accordance with 9.1.1.

A di agrammatic representation of Method A is given in Fig. I.

9.1.2.2 Method B - This method is intended to be used whereMethod A cannot be applied, for exa mp le, where the chamber used fortesting does not comply with the requirements for testing without forcedair circulation.

It is based on the assumption that the difference Do TI between thetemperature of a hot point on the test item and the ambient temperatureof the surrounding air in ' free air' conditions is more or less independentof the ambient temperature of the surrounding ail". This applies onlyif Do T 1 is less than 25°C.

The value of 6.T 1 may be extended to BO°C if the correct ionsdescribed in Fig. 2 are applied.

It should be noted that the corrections cover convection errors aswell as radiation errors.

For temperature difference Do T', greater than ao°c, the validity ofMethod B has not been verified.

The item suitably mounted in the laboratory and protected fromdisturbing influences, such as sunlight and draughts, shall be subjected atroom ambient temperature to the loading conditions specified for the lowtemperature at which the test is to be carried out. When temperaturestability has been reached, the temperature of the hottest point, or in thecase of larger or more complicated items, the temperature of a numberof representative points shall be measured. The temperature rise Do TlJwhich occurs at each point shall be noted.

If 6. T 1 is less than 25°C, testing shall proceed in accordancewith 9.1.1.

*Basic environmental testing procedures for electronic and electrical irems: Part IGeneral.

28

ITEM TEMPERATURE

AMBIENT TEMPERATUREWITH NO COOLING To

15 I 9000 ( Part II/Sec 4 ) • 1977

SId" 1 - Item load ed, Test inchamber condi t ions wilh chamberair-flow off and no cooling of itemIl:'m~raturl:'.

ITEM leMPERATURE SId" 2 - Item lnad ed. Test inchamber eonditlons with chamber air­flow on and no cooling, {';. Tv - {';. T'1'hall ~ small .

AMBIENT TEMPERATUREWITH NO COOLING To

ITEM TEMPERATURE r,

SPECIFIED TEST TEMPERATURE =TEST CHAMBER TEMPERATURE

StdX' 3 - Item loaded, Test inchamber conditions with chamber air­flow on and with cooling, Monit or ingon specified ambient \<".t temperature,

FIG. 1 DIAGRAMMATIC REPJlESENTATJON OP TEST WITHFO.CED AIR CIRCULATION FOR Msrxon A

29

II,,. (Put BiBee "). 1m I.I,. •t.• ••• 'lit...•

• .. •• .. ..

-, Ii- .... .."

'C • .. •

.JI. • rtf ..

• tI

PIVOT LINE.. • °C

" ttt

fa ..(AIotBIENT lEMPERATUREI •..

•..T.

(ITEM SURFACETEMPE'tATURE)

&-111:'btuti",. : An objee:t dissipating a certain power in free air a' 20·C reaches a surface

temperature at 7O"C.What will be its surface temperature when dissipating the same power in freeair at -4O"C ?

A_ : Draw a straight line from point +20·C on scale T. to point + 70°C on scaleT.; Dote itl intenection with the pivot line.Now draw a .traight line from point _40·C nn scale T. through lhi. Inre rsec"tion point 011 the pivot lin .. and read the new intersection wilh scale T. + 23"C.This is the required surface temperature.

FlO. 2 NOMOGRAM FOR CORRECTION FOR AMBIENT TEMPERKCUU

30

IS I 9000 (Part II/Sec 4 ) • 1977

If 6. Tl is greater than 25°C, the corrected temperature T I , basedon the specified lest temperature, shall be determined as describedin Fig. 2. The item shall bc introduced into the chamber while both itema nd cha mber are at room temperature. Then the item shall be switchedon or electrically loaded as prescribed in the relevant specification andthe chamber cooled down. The rate of change of temperature shall notexceed I"C per minute, averaged over a period of not more than5 m inutes. The final value of the chamber temperature shall beadjusted to a value at which the point measured on the surface of theitem at room ambient temperature reaches the above mentionedstabilized value TI . This temperature shall be maintained throughoutthe cond.rioning. T esting shall proceed in accordance with 9.1.I.fto 9.1.1.7.

Nary. - Wh~re there is a dUly cycle specified for items under t~t, then during theoff. load periods Ihe temperature of the chamber shall not fall below the: specified tottemperature ( Stl Fig . 3 J.

A diagrammatic representation of Method B is given in Fig. 3.

,T!M fE PERATURE

ROOM AMBIENTTEMPERATURE

ITEM TEMPERATURE Ts

Sltsg, 1 - Item loaded, Teat in laboratoryconditions with no forced air cireulatioa,Measurement of item temperature.

FlO. 3 DJAGRAIiOIATIC REpREsENTATION OF TEST WITH

FORCED AIR CIRCULATION FOR MaTHOD B

31

II." ( Pan Df8ect ).1m

'.2 Item Wltla AwdAdal Coou.. - The relevant soecllication Ihandefine the charactcriltic:s of the coolant supplied to the item. When thecoolant is air, care shall be taken that the air is Dot contaminated by oiland dry enough to avoid moisture problems.

'.2.1 c.litwS7'''' '1,.,.,.' flWt 'M~" - Item~ Oflhis type havecooling system which arc either self-contained or which obtain the coolantfrom an extraneous supply, with the coolant flow and return lion isolatedfrom th( hamber.

These items may be tested in accordance with 9.1.1 . with Method Aof 9.1-2 a~ an alternative.

9.2.2 Cooling S-"I"" • Nol [solaJed' from the Clunnhrr

a) Items in which fresh cool air is brought from an extra.leous sourceand then passes into the chamber after cooling of the item haitaken place. These items may be tested in accordance with '.1.1,with Method A of 9.1.2.1 as an alternative.

L) Items in which the cooling air is drawn from the, chamber and isreturned to the chamber after fulfilling its cooling function.These items may be tested in accordance with 9.1.1, withMediad A of 9.1.2.1 as an alternative, with the exception thatmonitoring shall be made on the air entering the item. Thetemperature of this air shall lie within the specified limits.

10. IN'TERMEDIATS MEA8U1lEMENTS

10.1 The relevant specification may call forJoading and/or measurementsduring or at the end of conditioning while the item is still in thechamber. If such measurements are required, the relevant specification .shall define the measurements and the period or periods after which theyshall be carried out. For these measurements. the item shall not beremoved from thejchamber,

Nonc- M~rernrnt! preceded hy recovery, which would nquire removal andrr.i.alroductioD of the itel:1J into the chamber, are not permiuible durin, tbecOlidirioni"l'.

10.1.1 If it is desired to know the performance of the type: of itembefore the rod of the prescribed duration, one additional lot will berequired for each specified duration. Recovery and final measurementsshali be performed separatelv for each lot.

11. RECOVERY

11.1 To remove droplets of water, the item may be shaken by hand ora bl:ut of air at laboratory temperature may be applied for a shortduration.

32

IS ..... ( Put D/Iect ) • 1m

11.2 The item shall then remain under.tandard recovery COnditioDi fora period adequate for the attainment oftempcrature stability, with aminimum of I hour.

lL2.1 When lCYeral iteuu are tested limultancoUJIy and where I hourI'eCOYeI'Y period iI inadequate the maximum period for recovery lhall be2 hOUR and all mcuurementa IhaJl be completed at the end of thiIperiod.

11.3 If requited by the relevant lpCCi&eations the item abalI be IWitchcdon or loaded and mcuured continuowly during the rccovat period.

lLt If the recovery conditions given are not appropriate for the item tobe tested. the relevant IpCCific:ation may Call for other I'eCOftrJconditions.

12. nNAL MBAIUaJtIIBNTS12.1 The item .haD be viaually inlpcc:ted and electrically and mechani.cally cbecbd .. required by the relevant .pecification.

l3. DUOlOfATlOM TO BB GI'9BM IN TBB IlBLBVA.MTIPBCD1CATION

13.1 When thil test iI included in the relevant .pecificatiOD, the following.detaila thall be Biven u far u they are applicable:

a) Preccmditioning;b) InitiallDCUUl'e&DCDtIj

c) Detaila of mounting or IUpportlj

d) State of item including cooling system during conditioning;e) Severity ( temperature and duration Df e:xpoIUn: );

() Intermediate mcuurem~g) Recovery, if non-standard;h) Final meaaarements; andj) Any deviation in procedure ..agreed upon between the parchuer

and theIDQ~.