FEAT RE FEA ATURE


SWIIT RELAY Norman M


TCHES & R


S & RELAYS


YS


RELAY CONTACT MATERIALS – DOES IT MATTER? If a relay ‘works’, why worry any further about its contact materials?


AY CONTACT MATERIALS – DOES IT M TTER? A rman Carnt of Finder UK ex ains w y access to the right contact m terial rnt of Finder UK expl


any relay users source a standard product, and with it, the standard


offering with respect to contact material. More often than not they are perfectly happy – never have a problem – and don’t give alternative materials a second thought. For some applications however, access to alternative contact materials can be essential.


POWE W C


atingswithintherange5to 0A remost silvernicke Silve


co tactma riate ra gswi ve


vernicke


relative hard resist


re eav


thereforeeforemakingitthat hea


re stanceto ref


thefullnominalcurre otherloadswhere


ot ec


avierelec no ad


oa teri


nypowerreays Silve cad


ow relay ye rs,part terialero ect ca oa velysmallnicke


rdenthesilve mevermechanically, toelectr ki


kel,silve cavercadmiumox kelhasbeenaro kelcont ec


ee nte ro ra


economicalandgoodperf materialandquiteofte manypowe verca


retheloa oo


admiumox 50yea mat


ateriialhasanimprovedrove resist weldingundercond in-rushcurre co tact


whensw ma riate matermat we


ru agre


nd conditionsof rr ntsthatresultfro


rent nfortfortunat


beenlimite 2002/9 pro


nviviro ee


itsuseinelectricalcontacts.And heso II’2011/6 dea mo


rohibite se


/95/EC.Initsfirst tedcomplet ec ri


ed


forindustristrialmonitoriringandco ro instrume tantation.Fo mind se raeve co ntri


ead neadline(unlessanyfurt months)of fo


strument sev ket ets(e.g. Forthisre


ndthatsuchDirectiverect veralmarke


mainta availabilityofreayvers ca


countriessuchasUSA tainav


va


cadmiumox Silve


gCdO, isproducedby pow /sinteri unlike AgNi,whichisatruealloy gr ev


Ag ri AgC ke Ag od owd r/ gN


grindingof eve


oftinox pers vendispersionof to 28 SEP EMBER 2016 28 SEPTEMBER 2016 || ELEC RO ELECTRONICS CS vertinox oxide–fo ec veisnot g.auto otive


ofJuly2016fo general se control


forge ed


we bowellboundinto envronment be


eethattheca ou


atre


contacto oils,inc ndesc Unf ree


torcoi ncandes atey,ev


tely,eve ears particularlyfo (10%) to riicalerosionof


POWER SWITCH tandardindustri


POWERSWITCHING Po


OWERSWIITCHING Powe switc st


edforreayswyswiithnominalcontact hera ge to50Aaremostcommonly ad be


se co tact ox xi


xide,andsilvertinoxide. roundalmostforever.ever.The tent %)isprimarilyto y,andtoincre


oxide nd ve


mostforev ri


rea easethe ofthecontactfa


ctrical load.Itiside fo re stive oa rentrat


atingof oadcurre


teoftenthest ys.


goodperfo ft


oxdexiidehasbe formingge


switcwitchinginductivect nd otorloads.Contacntact rosionislesse ed


foritsverygoo veandmot


tanc


eenpopularfo peha verygoodperformance ad


bee po


senedandinparticularthe ovedre stanceto ntact ofshort te


cetocontac ta romswtcswitchinglarg venthough rt


cadmiumcont nt tothebulksilve


tedbyedbythe‘Ro S’Euro eanDire rs edstedition,ca


ntalhazardzard, itsuse RoHS’


pea etely;butafurt ta


oodperf rm nc to oa part


fo ge ta


rt-term,high-peak,eak, rge


gh pe ct


scentla psandm ndsmallmoto ghvirtuallyallexpert contentissosma verthat


experts


sehasforsometime rope


cadmiumwas rtherrevirev


revievisioninthene ra


ke ee


rectiveec ve wa


evisionallow


/65/EUstillpermitsthis,butestablishesa rtherrev


next ex owe wed


contac ndtheso-called‘Roed RoHS pe


useandJuly2024 xt


SAorBRICS...),Find wi


oxideisamorerererecent nova ro


tomotve,orextra-EU nderwill


xtra foreseeaeeablefu re


oxideintosub-micro particles,the ofthiswithinthepowdereow redsilver,


oy.Theincre ronpart


powd ed ver, future. red


reasoeason,andkeepingin otappliedatall in ex


tyofrelayversionswithsilver fortheforesee


ve


byapowder/s teringpro ru


ec ntinnovatovation,andlike rocess— ne


oc ediblyfine Finder UK www.findernet.com


www.findernet.com T: 01785 818100


/ ELECTRONICS ELECTRONICS ke


atitpresentsno fo so


mallandso resent


so Figure 2: Figure 2:


Finder's 34 series 'flat pack' pcb relay uses Silver Nickel contacts - an economical and good performing general- purpose contact material


Finder's 34 series 'flat pack' pcb relay uses Silver Nickel contacts - an economical and good performing general-


purpose contact material ot rs. tors standardmat


atmuch orerom rerobust nd dealforresistveloadsat oftheconta


tactfaces, stunder


tact,andfor fo


rentisless.Itisan ra


general-purposepose rd


ateriterialfo for


forperhaps ce


se he ri


to Figure 1:


Relay contacts showing the effects of severe overcurrent due to mis- use


Relay contacts showi Figure 1:


ng


the effects of severe overcurrent due to mis- use


andthefinalhigh reghpressureforeformingtomakethe cont met AgS perf


ntactisapro tact


todaythehighperfoperf on,andno larg fa


alwaysasco od


way


form ays


now re av


eticulousprocesscontrol.Intheeahe rlearlyday gSnO2thequalitycontro rformance,of consist


roce ro


ocedcedure oc


efore tere ed


rgepegepeakinrushcurre facto correct rescent


rr


actorco rectioncapa fluoresc ntandot rc


hefundamenta ed


owheremore ru


rethatrequireeq resthemost ntro


atre


mo ma


st aysof


ofthesesinteredmat rateriialswasnot ste


tycontrol,andthereforef rethe se


resothaninthehand rentsprimari


pacitors


theinputcircuitryassociate savivinglamps,CFLorLED. The


ro


capacitorstorsisthatthere currentlimitingincirc theref


rent reforeeforelimite


andwillbe few


fe owe


othergasdischarg ry oc ted


ga sc


rsassociatoc ted rge


wa no


tentasitneededtobe oweve formanceofAg


ededtobe.However,wev r,


ceofAgSnOgSnO2canbereberelied ndlingof


of


rimarilycausedbypowbypower so ate wedwiith


owe edwith odmodernenergy rg


talproblemwithswtc reisvirtvirtuallynointe rcuit.Inst


stanta eo


po riwering-upswtc edmod variriablespeedinv t ntactwetactweldinghashist robleminthese eva ationof perf ofte


peed verte seapplica edct be valuat oftenpossibleto redictthelike ft po


rformanceof here os


form


ewthousandampereperes.Similarpea whenpow andva cont pro ev


beintheorderofse raeve sa


tedonlybyso rce rd ofsev


bysourc toricallybee


taneouscurrentsare ceandline pe veralhundre pe


switchingint tentional re


na


neimpedance re


ed


ee nverterdrives.Not sto ca


switchedmo epow ve


eakcurrentsoccur od powersupplies otsurpri aj


red, ifnot re


owe risingly, oftheapplicationaga st nown ow kelyimprov ove


cations,butwithcareful gainstkno


eenamajor re


ca fu ma


oftherelayundersuchcondconditions, itis topre


rovementthat y,


ota oc


ce, nto


gelamps,andalso dern ne gy


so ysof ot ke


ow wiwerswtchingupto 0Aisgenera pos stand rd nd strialreays


relay


to50A generallypo ys,whilst gh


ovinceofcontactors terialsusedfo relay


sthighercurrentsare


usuallytheprohe virov ceof ntactotact rs.Theprincrinciple contactmat rat


ossiblewi re ts re


with explainswhy access to the right contactmaterial is important achange getoAg


manufacture perfperfo test


testandev rt


formance eva


AgSnO wi shorttimescale.


fact rerwillnee cedata valuate ca


RELIABLESW CH At


re ri ex xt portant


gSnO2willbring.However, eed


taandtheabilitytotytoexperimentally teinarepe ta


edanextensivebankof peri


repeatablemanner,


RELAELIIABLE SWITCHINGATLO otherendof


re cernedwithcont ro od


togetogether–we reconc ne reliableandlowreow tastance QuiteQutesimply, he owe beingswtched,themore surface topro


y,thelow be rf


understoders ootoodbyrelay take


betwee ta


eve


betweenthecontacts nd clea


kentoensure etwe


eanlinessare Nev


orindeedshould,ex subjec ofcont shouldav mat


deed rt


ate goodpow


good owe swtc ow-lev swtc


pow go


edtoswtchbot


vertheless,there re exercise


voioidusingreays relay


facesto roduceagoogoodoodconne odbyreaymanufact rers rethat


switc ed he od


tainedduri ta r,andina


RELIABL SWIITCWITCHING AT LOWPOWEPOWERLEVEL Attheot conce ed


ofthecurrentscalewe renot ntacttactserodingaw


ceconne ff nection.


werthevoltage nd redifficultitisfo


weareconcernedthatcontactsmake resist


OW POWER EV sc weare ot away,orwe atcontac


vo geandcurrent rent


contac andthatminimumleve of remainta


atthere adeq te ressure ev


rearechoicesthat


bjectof ntacttactmateriterials.Bro avo


terials,asthecharact rst


needtoswitc bo pow thentheonlyre sticopt powerreay ted


realist


owe contacts,asgoldisexpensive ndwould simplybeburntoffunderpow conditions.‘A‘Apparent bec willbe od occa switc


‘A‘Anomaly’since powercont ct be


pow


ceitmake go


expe ntof


swtchingapplica thescale.There tothis.Thego thickness–avo flashthat


sc ca to ne


mechanicallyweca wearthro gh operatpera be


Thisisnot ec


ec se ations;so


low eve go


becausethereay onc


easonfo


re so forthisisavery terestingmixof andchemistrystryatplay. BacktBa raktrackingalitt


acki switc swtching?


no bad.Thespecificat minimumva


relayspe isnot


otba


switchingloa of re


we


UK’srangeofre yshasaspecifiedminimum swtc


ra geofrelays


g?Typicallya16Apowe pe


oadof10V/ V/1 mA/ /10mA/1A/1000mW


pecificallydesignedtoswitc pe


valuesshouldbemebemet.


gnedtoswtchloadsupto kW, ationmea


mW, oa


eansthatallthree ee


to4kW re


fora W,


kelytobeworsworsethanbaresilve veryinterest


be go


ttlesensetogo veandwo


se se


betheoddoccasionwhenthissovesolvesamixe cation ithreliability reis,howevewever,ave


w re atisty ca of


voidingany uggestgestionof typicallyofth orderof otjustbeca se


goldmustbe atedto av


sodonotbeotbemistaketakeninto relayonlyoperate


nceamonthallwillbewebewell–itwon’t!Fo reliable owlev swtc goldflashislike rea


peratesinyo wo


at


velswitchingagoldplat se


yourapplication Forre


atewillbeexcbe xcellent nt,buta


bare ver.The ofphys


ysics


ttle,whatdowemea bylowlev 6Apowerreow relayfro ecfi


nder W,whichfo


eanby ow eve romFind


vel


ewthousand tothink


fe


owev r, veryimportantaspect stbeplatedtoasignificant s gg


ry port bo


tyatbot


othendsof ta fi


pe go e rd of0.2micro


stbecausesuchathincoa wi roughwithinafew


oatingwill kiingthat


of ec


ofusingagold ron.


rent’be a seweknow atthere xed


ff nd power-swtching ec usewe no


owe switc owthat re ed edcontacttacts.


ringmanufact re ce


oo powerswitchersterste dtoworkagainstreliable low eve ee


yswithpowercont ct racteriisticsthatmad n towo


ow contact velswitching.Bu occa na


othpoweowerandlow-levow eve wo


keslitt


adethem ga stre


Butoccasionallytherearisesthe velcirc


re rise


owe relaywiththeappareparentanomalyof av gold-plate no y’


ptionwouldbetobe seec no


toselecta ofhaving


rcuits; ct


goldplat ate te


oadlyspeaking, powe


pe velsof facture. attheusercan,


xercsewhenitcomestothe roa


eaki g,one


facturersandgreatcare reisadequatepre


re


nection.Thisiswell reat


forthecontacttact we


reis


OWER LEVELS way, welding


EVELS kea


owevewev r,there veba


of relay


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56