An introduction to electrical safety testing in accordance with IEC Innovating Together

Transcription

1 A itroductio to electrical safety testig i accordace with IEC Iovatig Together

2 World s smallest, automatic, electrical safety aalyser Itroducig the Rigel 288 Cotets Foreword 2 1 Itroductio Electrical Curret The Huma Body IEC Body Model 6 2 Medical Electroic Equipmet Commoly used terms ad 7 defiitios i IEC Symbols ad Markigs Product ifecycle 9 3 IEC I-Service Test Requiremets 11 Iovatig Together 8 IEC eakage Measuremets Method Characteristics Direct eakage Differetial Method Alterative Method Equipmet eakage Equipmet eakage Direct Method Equipmet eakage Differetial Method Equipmet eakage Alterative Method Applied Part eakage Applied Part eakage Direct Method Applied Part eakage 30 Alterative Method 8.4 Secodary Earth Problems ive to Earth Voltage 33 The Rigel 288 electrical safety aalyser Time-savig data ad asset maagemet, speedier battery-powered leakage tests ad peace-of-mid through better traceability. Small. Speedy. Smart. Visit to fid out more Or call +44 (0) Itroductio to IEC 62353: How does IEC compare 13 with IEC 60601? 4.2 Techical Cosideratios Test Frequecy Vital Preparatio 14 5 Visual Ispectio 14 6 Earth Bod Testig Earth Bod Test Cosideratios Precisio vs Accuracy 17 7 Isulatio Resistace Test Isulatio Resistace EUT to Earth Isulatio Resistace Applied Parts Isulatio Resistace Applied Parts 20 to Mais 7.4 Isulatio Test Pass Fail imits 21 9 Record Keepig Comparig Data Coclusio Cosideratios ad Recommedatios 35 Appedix A 37 Pass / Fail imits of IEC Appedix B 38 IEC Collateral Stadards Appedix C 39 IEC Particulars Stadards Appedix D 41 Patiet Eviromet Appedix E 42 Example Documetatio Template Iovatig Together Part of 1

3 Rigel Medical Compay Profile The healthcare market is techology drive ad with a global demad for icreased patiet safety, there has ever bee a more prudet time to demad more from your test equipmet. rigelmedical.com Iovatig Together Iteratioal stadards for the developmet ad maufacturig of medical devices put greater emphasis o risk assessmet ad aalyses of data. So, there is a icreased eed for test equipmet that allows the user to automate data capture ad esure validity of test results for better maagemet of risk. Our rage of dedicated biomedical test equipmet is vital i verifyig the safety, accuracy ad performace of medical devices, ad has become itrisic to the edeavour to raise the stadard of patiet safety across the globe. Rigel Medical products are sold worldwide through a iteratioal etwork of agets ad distributors. Rigel Medical is part of the Seaward Group of compaies. 1 Itroductio This guide covers a basic itroductio to electrical safety, defiitios of a medical electroic device, the IEC stadard ad a i-depth overview of the IEC publicatio. The structure ad topics discussed i this guide are writte i a way such that the widest possible audiece ca beefit. There is a directly proportioal relatioship betwee the electrical curret (ampere) through ad the electrical potetial (volt) across the coductor (ohm). This is commoly kow as Ohm s law. V (a b) = I * R The force required to deliver the electrical curret across a potetial differece is kow as power, which is represeted i Watt s. Power is a product of voltage (volt) ad curret (ampere): Foreword This booklet is writte as a guidelie for people ivolved i testig medical electrical equipmet (ME equipmet). The aim of this booklet is to help the reader to: Appreciate the basics of electrical safety. Uderstad the reasos behid ad the purpose of the IEC publicatio. Provide a uderstadig of the beefits of usig the differet tests available, i order to help them prepare the adoptio of the IEC stadard. This booklet caot be cosidered as a replacemet for the IEC publicatio, which ca be purchased through the official IEC website, All reasoable care has bee take to esure the accuracy of the iformatio, referece figures ad data has bee take from the latest versios of various stadards, guidace otes ad recogised best practices to establish the recommeded testig requiremets. However, Rigel Medical, their agets ad distributors, accept o resposibility for ay error or omissios withi this booklet, or for ay misiterpretatios by the user. For clarificatio o ay part of this booklet, please cotact Rigel Medical before operatig ay test istrumet, uder relevat legislatio. o part of this publicatio shall be deemed to form, or be part of, ay cotract for traiig or equipmet uless specifically referred to as a iclusio withi such cotract. Rigel Medical assumes that the readers of this booklet are electroically techically competet ad therefore, does ot accept ay liability arisig from accidets or fatalities resultig directly or idirectly from the tests described i this booklet. 1.1 Electrical Curret Electrical curret is a secodary eergy form cosistig of the flow of charge (i coulomb) through a circuit over a certai time period, ad is depicted i ampere. 1 = Q/t or 1 Ampere = 1 Coulomb/1 secod Whe electrical curret passes through a coductor or electrical circuit, it geerates a electrical potetial (depicted i volt), see figure 1. Figure 1: Ohm's aw A Electrical curret (I) Electrical potetial (Va-Vb) Ohm s aw V(a-b) = I x R Coductor resistace (R) B Power i Watts P = V x I Aother factor of electricity is electrical eergy (joules), a product of electrical power (watts or joules/secod) ad time (secods). The relatioship is provided below: Eergy i Js E = P x t Power i Watts P = I² ز Eergy i Js E = (V² x t) / R Power i Watts P = V² / ز Eergy i Js E = I² x R x t The relatioship betwee curret, voltage ad resistace ca be equally applied to water ruig through a pipe. I both cases, electric curret ad water prefer the path of least resistace. The larger the cross sectio of the pipe or coductor, the easier water or curret ca flow at a certai water pressure or voltage. See figure

4 Iovatig Together Figure 2: Example showig water followig path of least resistace The thier or loger the water pipe, the more water pressure is required to deliver the same litres per miute (flow or curret). The thier or loger the coductor (assumig a particular specific resistace of material), the more voltage is required to deliver the same curret. 1.2 The Huma Body A sigificat part of the huma body is made up of water alog with dissolved ios ad mierals, which are capable of coductig electrical currets. Broadly speakig, the hazard of such electrical currets would deped o: excite or stimulate muscles of the respiratory system (itercostals). The most critical muscles are those i the huma heart, which are drive (excited) by very tiy amouts of electrical currets. Whe the heart is exposed to exteral electrical currets (electrical shock), the heart ca lose its ormal sius rhythm, required to sustai a healthy blood circulatio, ad move ito vetricular fibrillatio. This stops the circulatio of oxyhaemoglobi (oxygeated blood cells) to the brai ad orgas ad whe left utreated, will result i death withi 15 miutes. <1 A Serious burs ad muscular cotractio of such a degree that the thoracic muscles costrict the heart (Data adapted from published research by Professor C.F. Dalziel) The graph below (figure 3) highlights the differet effects of electrical curret o the huma body as uderstood by Dr. Howard M. Hochberg i. Figure 3: Impact of curret o the huma body, adapted from research by Howard M. Hochberg, 1971 Water Stregth of the curret Path of the curret Total impedace for the curret path Frequecy of the curret Duratio of the curret beig applied Electrical currets ca be extremely dagerous to the huma body. The eergy (power ad time factor) released by electrical curret passig through huma tissue ca geerate burs ad Electricity Curret or flow itre / secod Curret Ampere (coulomb / secod) Pressure e.g. BAR or PSI Voltage Volt Resistace Effected by pipe cross sectio ad legth Resistace I ohm (Ω). Effected by coductor cross sectio, legth ad material Iroically, the most commo treatmet of vetricular fibrillatio is the use of a defibrillator which delivers a very high curret pulse, up to 100A across the heart. The eergy i that high curret pulse is sufficiet to temporarily clamp the heart muscles (ie stop the heart completely) before releasig it agai ad allowig the heart to resume i its ormal sius rhythm. Cosider the followig examples of a macro shock showig the effect of a 50 / 60 Hz curret o the huma body whe applied to the ski for 1 3 secods (o-ivasive): ma Curret just oticeable whe applied to the figer tip 6 16 ma Paiful shock, uable to let go, caot be tolerated over 15 miutes ma Vetricular fibrillatio, respiratory arrest, leadig to death 4 5

5 Iovatig Together 1.3 IEC Body Model To esure a stadardised method of simulatig the impedace of the huma body, measuremet circuits have bee desiged to simulate the average, typical electrical characteristics of the huma body. These measuremet circuits are referred to as a Body Model or Measurig Device (MD i IEC ). The mai impedace is formed by a 1kΩ resistor, show i figure 4. Figure 4: Example of a measurig device MD to IEC R1 Z R2 C1 V Voltage measurig istrumet b) 2 Medical Electroic Equipmet Heath facilities icludig hospitals, surgeries, GP practises, veteriaria cliics, detists etc. use a variety of electrical equipmet. The equipmet rages from specialist medical, laboratory ad IT equipmet to ordiary domestic appliaces. Ay electrical equipmet for the purpose of treatig, moitorig or diagosig a patiet s coditio is classed as a medical electroic device accordig to IEC 60601, the global harmoised stadard goverig the desig ad approval of medical devices (see 3). R 1 = 10k Ω ±5% a) R 2 = 1k Ω ±5% a) C 1 = µf ±5% Frequecy (ƒ) i Hz a) Measurig device b) Frequecy characteristics OTE: The etwork ad voltage measurig istrumet above is replaced by the symbol followig figures. a) o-iductive compoets b) Impedace >> measurig impedace Z c) Z(ƒ) is the trasfer impedace of the etwork, i.e. Vout/i, for a curret frequecy ƒ. Relative magitude c) (db): 20 log Z(ƒ) Z(ƒ-10) MD i the The official defiitio of medical electrical equipmet accordig to IEC is: Electrical equipmet, desiged for treatmet, moitorig or diagoses of patiets, powered from ot more tha oe coectio to mais supply ad which are ecessarily i physical or electrical cotact with the patiet or trasfers eergy to or from the patiet or detects such eergy trasfer to or from the patiet. Medical ad o-medical electroic equipmet ca also be combied ito a medical electroic system. To esure safety of patiet ad operator, this system must meet the desig requiremets of IEC The defiitio of a medical electroic system is; Combiatio of equipmet of which at least oe is classed as medical electrical equipmet ad as such specified by the maufacturer to be coected by fuctioal coectio or use of a multiple portable socket-outlet. 2.1 Commoly used terms ad defiitios i IEC / Equipmet uder test The equipmet (EUT) which is the subject of testig. Device uder test The device (DUT) which is the subject of testig. Applied part Part of the medical equipmet, which is desiged to come ito physical cotact with the patiet, or parts that are likely to be brought ito cotact with the patiet. Patiet coectio Idividual physical coectios ad / or metal parts iteded for coectio with the patiet, which form (part of) a applied part. Patiet eviromet Volumetric area i which a patiet ca come ito cotact with medical equipmet or cotact ca occur betwee other persos touchig medical equipmet ad the patiet, both itetioal ad uitetioal. (see appedix D) F-Type applied part Applied part which is electrically isolated from earth ad other parts of the medical equipmet. i.e. floatig. F-Type applied parts are either type BF or type CF applied parts. Type B applied part Applied Part complyig with specified requiremets for protectio agaist electric shock. Type B applied parts are those parts, which are usually Earth refereced. Type B are those parts ot suitable for direct cardiac applicatio. Type BF applied part F-Type applied part complyig with a higher degree of protectio agaist electric shock tha type B applied parts. Type BF applied parts are those parts ot suitable for direct cardiac applicatio. 6 7

6 Iovatig Together Type CF applied part F-Type applied part complyig with the highest degree of protectio agaist electric shock. Type CF applied parts are those parts suitable for direct cardiac applicatio. Class I Equipmet protectio agaist electric shock by (earthed) additioal protectio to basic isulatio through meas of coectig exposed coductive parts to the protective earth i the fixed wirig of the istallatio. eakage curret Curret that is ot fuctioal. Macro shock o-ivasive applied curret which passes from oe side of the body to the other, typically had to had or had to foot, ad therefore crossig through the heart. Micro shock Ivasively applied curret which passes directly across the heart tissue. Class II Also referred to as double isulated. Equipmet protectio agaist electric shock is achieved by additioal protectio to basic isulatio through meas of supplemetary isulatio, there beig o provisio for the coectio of exposed metalwork of the equipmet to a protective coductor ad o reliace upo precautios to be take i the fixed wirig of the istallatio. OTE: Class II equipmet may be provided with a fuctioal Earth termial or a fuctioal Earth coductor. 2.2 Symbols ad Markigs The IEC defies the requiremets for iformatio / data to be preset o the medical equipmet's ameplate, i order to form a uambiguous idetificatio of the equipmet. Protective earth Dedicated circuit iteded to carry the fault ad leakage curret i class I equipmet ad to be coected to the protective earth termial. Fuctioal earth Dedicated circuit iteded to provide a electrical screeig ad to be coected to a fuctioal earth termial. ie to earth voltage Applied voltage betwee the live wire ad earth coductor, affectig the leakage curret. Iformatio must iclude; maufacturers ame, model umber, serial umber, electrical requiremets etc. The IEC stadard refers to a large variety of symbols for use o medical equipmet, medical systems, accessories ad other related parts. A full overview of the symbols used i IEC is provided i table D1 of the stadard. For the purpose of this booklet, a selectio of the most commoly used symbols is displayed opposite. 2.3 Product ifecycle For may years, ME equipmet has bee subject to extesive approval processes from cliical trials, to type testig all the way through to ed of productio lie testig, to esure it operates properly before leavig the factory. I additio, maufacturers recommed that regular electrical safety ad essetial performace checks are carried out to esure there s o risk of harm ii to the patiet ad operator oce the device goes ito service. Figure 5 - Safety stages through a product lifecycle REPAIR (IEC 62353) DECOMMI- SSIOIG MAITEACE (IEC 62353) DESIG (IEC 60601) SAFETY OPERATOR TRAIIG TYPE TEST (IEC 60601) ACCEPTACE ED of IE TEST 8 9

7 Iovatig Together R&D Type Testig Productio Acceptace Prevetative Maiteace Repair Maiteace Decommissioig Durig this stage a cocept is subject to iitial & cliical trials. Electroic ad mechaical desig of the product (where applicable) must be i lie with the IEC stadard. Durig this stage the product is expected to have completed the cliical trials ad subject to type testig is ready for marketig. The hardware ad software of the product is verified agaist the desig stadards. Whe CE markig is obtaied, the medical product ca be marketed. Durig this stage the products are beig assembled, tested ad ispected for release ito the market place. Oce a medical device reaches the cliet, a acceptace test is performed. This test is to verify that the device is delivered i a acceptable coditio, complete without ay defaults ad available with all specified accessories. A performace ad electrical safety test are ofte completed as part of a referece for future maiteace. (Plaed) Prevetative Maiteace or PPM is a process whereby the device is subject to scheduled ispectios ad tests, i order to verify that the safety ad operatio are withi acceptable levels ad criteria. This is referred to as pro-active maiteace. Should a device create a fault or require a upgrade, the device will be susceptible to further ispectios ad testig. This is referred to as re-active maiteace. At the ed of a product lifecycle, is the decommissioig stage. The device, depedig o its fuctio ad material cotet may be required to follow a set process (i.e. A evirometally hazardous product will eed to follow a recyclig process. Uder certai coditios, the device ca be made available to other orgaisatios i which a secod lifecycle ca start at the acceptace stage. 3 IEC ME equipmet must meet the desig requiremets as set out by the IEC (a harmoised stadard), which has bee adopted by all IEC member states. This sets out all the desig criteria for producig equipmet that is electrically ad mechaically safe, as well as placig the ous o the maufacturer to uderstad how to reduce the risk of harm whe patiets ad operators are exposed to their medical devices. All tests relatig to the electrical safety of ME equipmet ad devices ca be categorised ito two categories: MEAS OF OPERATOR PROTECTIO (MOOP) - Meas of protectio for reducig the risk of electric shock to persos other tha the patiet. MEAS OF PATIET PROTECTIO (MOPP) - Meas of protectio for reducig the risk of electric shock to the patiet. To esure that ME equipmet does ot pose a electrical hazard to the patiet, or ay other perso, it is desiged with sufficiet levels of isolatio (dielectrics) to reduce the amout of electrical leakage curret to a acceptable ad safe level - as low as 10µA iii. This is achieved by separatig high electrical potetials from ay coductive parts, accessible to the operator or patiet. Dielectric stregth is prove by applyig a high voltage betwee high ad low electrical potetials. However, this could lead to a breakdow of the isolatio ad would therefore be referred to as a destructive test. A safer way to test the effectiveess of dielectrics is to perform a umber of electrical leakage tests, such as leakage origiatig from the power supply to the eclosure (MOOP) or protective earth wire (MOOP & MOPP) or eve to the patiet coected parts (MOPP). I IEC 60601, the test requiremets for electrical leakage must be carried out uder the worst possible coditios to esure absolute safety. This is achieved usig a elevated mais at 110% of the highest expected voltage (i.e. at 240V mais this would mea testig at 264V). Precoditioig of the ME equipmet is required prior to testig. Tests are doe uder ormal coditio (o fault coditios), ad icludig ay oe of the specific ad relevat fault coditios. Testig the protective earth circuit desig for sufficiet curret carryig capabilities is achieved by stressig the desig, passig a miimum test curret of 25 ampere RMS through the circuit for a miimum of 10 secods. At these curret levels, time duratio ad resistace values (<0.1 Ohm iteral equipmet resistace), eough eergy will be created to covert curret ito thermal heat. By observig the thermal profile of a desig, oe ca establish parts of the desig that might eed to alter i order to reduce the electrical resistace ad thus the coverted eergy; E = I² R t Coductig such tests durig the developmet ad approval stages of a products life cycle, provides sufficiet levels of cofidece that the ME equipmet meets the desig requiremets of IEC Oce a desig is approved for maufacturig ad marketig, a subset of tests will suffice to esure the product has bee built ad assembled to the required product quality ad safety requiremets. This subset of tests is commoly referred to as routie tests ad are ot clearly defied i IEC thus ca vary betwee maufacturers ad product desigs. It s for this reaso that the ew IEC 62353:2014 makes a recommedatio that IEC ca be used durig fial testig ad before puttig a piece of ME equipmet ito service. 3.1 I-Service Test Requiremets IEC does ot provide ay guidace o routie test requiremets. This has led to differet iterpretatios across the world o how to apply IEC to routie test scearios. Oce a medical device leaves the factory, a umber of potetial test scearios arise, icludig: Acceptace testig - also referred to as a iitial or referece test. This test is carried out prior to a ew medical device beig authorised for use ad is udertake to esure correct ad 10 11

8 Iovatig Together complete delivery. Acceptace testig is ofte ot limited to a electrical safety test, with some basic fuctio tests also beig applied to verify correct performace. Routie testig - also referred to as plaed prevetative maiteace (PPM). This form of testig is ofte coducted at fixed time itervals, which vary betwee types of equipmet, maufacturers recommedatios ad risk assessmet procedures udertake by idividual BME or medical physics departmets. Routie testig is ot limited to safety testig ad ofte icludes the verificatio of correct fuctioality. After service & repair testig this is carriedout followig a repair or product upgrade ad is ofte part of a service carried out by i-hospital mechaical or cliical egieerig teams. I may cases, more rigorous electrical safety testig is eeded after the replacemet of compoets or recofiguratio of medical devices. 4 Itroductio to IEC 62353:2014 As its full ame implies, IEC Medical Electrical Equipmet - recurret test ad test after repair of ME equipmet, defies the requiremets for electrical safety testig of medical electrical (ME) equipmet ad systems durig routie itervals. Followig the eed for a uified approach to routie testig, the first editio of IEC brought together a set umber of tests to allow its users to test the MOOP ad MOPP dielectric itegrity via two distict leakage curret tests: EQUIPMET EAKAGE - Testig the total leakage geerated from the icomig mais to the rest of the equipmet (cofirmig itegrity of the MOOP). PIED PART EAKAGE - Testig that floatig applied parts (BF&CF) remai at a acceptable floatig level (cofirmig itegrity of the MOPP). I meetig this requiremet the IEC icorporates tests beyod those of type testig. Specifically, it seeks to provide a uiformed ad uambiguous meas of assessig the safety of medical equipmet, whilst maitaiig the relevace to IEC ad miimisig the risks to the perso coductig the assessmet. Importatly, the IEC stadard recogises that the laboratory coditios described i the IEC 60601, such as elevated mais, isolated T (Terre eutral) supply, temperature ad humidity coditios caot always be guarateed whe i-service testig of medical devices is udertake. More commoly, secodary earth coectios caused by data cables ad systems, provided measuremet errors that ca ow be overcome by IEC Aother factor raised is that equipmet could potetially be damaged by applyig type tests (IEC 60601) durig i service testig ad could therefore represet a potetial dager to users. Oe of the most sigificat chages to the 2014 editio is the recommedatio to test accordig to IEC at the fial productio lie stage ad also before equipmet goes ito service. This will allow recurret testig to be directly comparable with factory tests, providig for easier greater observatio of ay variatios i leakage measuremet. ew i the IEC 62353:2014 editio are a umber of suggested leakage tests that would isolate the touch leakage curret or patiet leakage curret. Both tests form part of the equipmet leakage curret. However, if a maufacturer wats to provide a specific measuremet, the IEC 62353:2014 ow provides guidace for these tests to be coducted i the iformative sectio of the stadard these might be cosidered whe the equipmet leakage values have chaged from previous measuremets. The 500V DC isulatio tests i the 2014 editio have also bee supplied with recommeded pass/fail limits, take from iteratioally accepted practices for isulatio testig of electrical equipmet. While isulatio tests are optioal, it s always recommeded to check with the equipmet maufacturer if this ca be coducted without damagig the equipmet uder test. The stregth of IEC eables those who carry out testig to coduct a summary of tests o the iput of medical devices (equipmet leakage) ad o the output of the medical equipmet (applied part leakage). As will become evidet from the followig chapters, the time savig associated with IEC will also allow for more time to be spet o visual ad fuctioal testig. 4.1 How does IEC compare with IEC 60601? Although IEC is a type test stadard goverig the safety of the desig ad maufacture of ME equipmet, for decades biomed ad cliical egieers have used the IEC as the basis for regular testig or after service / repair of medical devices. ocal variats of IEC have also bee adopted ad used as a basis for routie testig. It is clear that most commoly used electrical safety aalysers will oly provide meas of testig to a subset of tests described i IEC ad ofte exclude destructive tests such as high voltage dielectric testig, costat curret 25A testig, SIP / SOP fault coditio testig to aid portability ad safety of the operator. So what are the mai implicatios of testig to IEC ad how does it differ from the very well established ad widely uderstood requiremets of IEC 60601? 4.2 Techical Cosideratios The aim of IEC is to provide a uiform stadard that esures safe practices ad reduces the complexity of the curret IEC stadard. All tests are based o leakage testig to IEC 60601, but a umber of aspects to improve safety ad practicality have bee removed. The most sigificat chages are: o pre-coditioig of equipmet uder test o elevated mais o destructive testig Testig uder sigle fault coditio oly 12 13

9 Iovatig Together Summarisig leakage ito iput ad output safety Testig at applied part level rather tha at patiet coectio Differet methods for coductig leakage tests subject to practicality May IEC tests are directly related to IEC tests, which is show i figure 6 below. Figure 6: Comparig IEC with IEC IEC IEC Earth leakage Equipmet leakage DIR/DIF Earth leakage SFC eutral Equipmet leakage AT Eclosure leakage SFC earth Equipmet leakage DIR/DIF Patiet leakage Equipmet leakage (eclosure probe discoected) Mais o applied parts Applied part leakage Measured values Some are calculated Oly direct method Direct/differetial ad alterative 4.3 Test Frequecy To esure safety ad performace is maaged throughout the lifecycle of medical electrical equipmet, maufacturers must specify the itervals for testig ad ispectig their devices. The basis for this is risk assessmet: the likelihood of occurrece ad severity of icorrect operatio. Cosideratio has to also be give to the applicatio of the product, frequecy of use, the operatioal eviromet ad operator competecy. IEC 62353:2014 recommeds followig the maufacturer s istructios o test itervals. If this is ot available, a test iterval betwee of betwee six to 36 moths is suggested depedig o risk assessmet. 4.4 Vital Preparatio Although IEC was first published i May 2007, may compaies ad orgaisatios are still i the process of makig chages to their approach to electrical safety testig. To icorporate the IEC test philosophy ito ay orgaisatio requires ecessary preparatio. Optios for choosig the correct set of tests, requires a uderstadig of the purpose ad beefits of usig the differet tests available. Although the ous will ievitably fall o the maufacturers of medical devices to advise o appropriate i-service test procedures for their ow equipmet, IEC clearly has a impact o medical service compaies, biomed s, medical physics, cliical egieerig ad other techical departmets. To help all those likely to be affected by the itroductio of IEC tests, a summary of the test requiremets is provided withi this guidace booklet. This IEC guidace booklet is iteded for geeral iformatio oly ad caot be cosidered a substitute for the full versio of the stadard. 5 Visual Ispectio The process of visual ispectio is ot clearly defied by IEC 60601, however visual ispectios form a critical part of the geeral safety ispectios durig the fuctioal life of medical equipmet. I most cases, 70% of all faults are detected durig visual a ispectio. A visual ispectio is a relatively easy procedure, which is carried out to esure that the ME equipmet i use, still coforms to the specificatios released by the maufacturer ad has ot suffered from ay exteral damage ad / or cotamiatio. The followig ispectios ca be icluded: Housig / Eclosure - ook for damage, cracks etc. Itegrity - ook for obstructio of movig parts, coector pis etc. Cablig (supply, applied parts etc.) ook for cuts, wrog coectios etc. Fuse ratig - check correct values after replacemet. Markigs ad labellig - check the itegrity of safety markigs. Itegrity of mechaical parts - check for ay obstructios. 6 Earth Bod Testig Protective earth coductors are desiged to allow a safe ad easy path (low resistace) for electrical leakage ad fault currets to flow, which allows the protective fuses or lie curret moitors (RCD s, GFI s) to operate ad iterrupt the supply voltage. This provides a importat meas to reduce the risk of ijury by electric shock ad also stops the release of eergy which may ultimately lead to fires. I class I electrical equipmet the protective earth coductor resistace eeds to be of sufficietly low value, i order to prevet the voltage o exteral metal parts risig to a level where the shock potetial presets a hazard to life. Although may class I medical devices are supplied with a earth referece poit, most, if ot all, medical devices require multiple earth bod tests to validate the coectios of additioal metal accessible parts o the eclosure. A test curret is applied betwee the earth pi of the mais supply plug ad ay accessible metal part (icludig the earth referece poit) via a dedicated earth bod test lead (clip/probe). Figure 7 shows a represetatio of the earth bod test. Figure 7 - Earth bod test i class I equipmet PE Ω For fixed istallatios a poit-to-poit cotiuity measuremet ca be made by fittig a secod lead ito the aux earth socket. The resistace is the measured betwee the two leads

10 Iovatig Together The IEC requires a miimum test curret of 200mA, either AC or DC. Whe usig a DC test curret, the resistace must be tested i both polarities of the test curret. The highest readig will determie the pass or fail result of this test. The ope circuit voltage of the curret source should ot exceed 24V. The test limits i IEC are set to: 100mΩ 300mΩ 500mΩ For a detachable power cable up to 3 metres For a class I device icludig power cable (ot exceedig 3 metres) For a medical system cosistig of several medical ad o-medical pieces of equipmet. See defiitio of a medical system i IEC : 2005 Figure 8: Example of icreased cotact resistace i sprig loaded cotacts 6.1 Earth Bod Test Cosideratios Checkig the protective earth durig routie testig is differet from that udertake durig the type test approval. While testig at the desig stage highlights the capacity of the desig to cope with fault currets, the quality of the protective earth is more importat durig routie testig. It s importat to remember that cotact resistace ca be easily overlooked whe usig the required 25A i IEC because high test currets ca temporarily repair poor mechaical cotacts iv. Cotact resistace is made up of two compoets: 1. Restrictio resistace (where the coductive cross sectio is reduced) 2. Film resistace (the possible resistive layer betwee the two coductive surfaces due to film oxidatio, dust etc.) ower test currets, typically less tha 8A RMS, are uable to temporarily overcome cotact resistace (both film ad restrictio resistace) ad thus highlight problems as a result of agig (icreased restrictio resistace due to softeig of sprig loaded force o the cotacts typically foud i removable power cords, see figure 8). High test currets (10A or more) ted to provide a more costat readig (high precisio) eve if there is a potetial costrictio i the protective earth path. High test currets might also be destructive to parts of the DUT which are coected to the protective earth but have a fuctioal purpose (e.g. screeig). Therefore, IEC recommeds that protective earth coectios are tested with a 200mA test curret to highlight agig power cords although high readigs could be as a result of film resistace which ca be removed. Combiig a high pre-pulse (to clea the film resistace) ad measurig with a low curret to show up ay restrictio resistace, is the most accurate way to determie the quality of the protective earth path. 6.2 Precisio vs Accuracy Whe performig a earth bod test, remember that accuracy must take precedece over precisio as havig a cosistetly wrog measuremet is precise but ot very accurate. Usig a high test curret might provide a higher precisio (see figure 10), but would ot ecessarily give you a more accurate represetatio of the quality of the protective earth circuit due to its capability to temporarily repair costrictio resistace. ower currets are ot able to provide a false positive ad are therefore fail-safe. ow test curret oly (see figure 9) - Possible low accuracy ad low precisio as high readigs could be due to film or costrictio resistace. High test curret oly (see figure 10) - Possible high precisio but low accuracy as agig cables with poor cotact resistace will give the same readigs as a brad ew good cable. ow test curret with high curret pre-test (see figure 11) - Cleas film resistace, ay high readigs would be dow to poor cotact resistace thus high accuracy ad high precisio. A separate white paper o high vs low test currets is available free of charge o our website at Figure 9: ow accuracy - low precisio Figure 10: ow accuracy - high precisio Figure 11: High accuracy - high precisio ow pressure applied (high resistace) Icreased pressure (low resistace) 16 17

11 Iovatig Together 7 Isulatio Resistace Test The risk of uacceptably high electrical fault currets ca be miimised through desig criteria i.e. through effective levels of electrical isulatio/isolatio. Such isulatio ca be achieved through physical spacig (creepage ad clearace) of compoets, choice of compoets ad dielectric materials, while esurig the device operates properly. The effectiveess of electrical isulatio is tested through electrical leakage measuremets (results i ma or µa) while the level of isolatio is ofte tested usig a dielectric or isulatio test. Durig a dielectric, or hipot test (further iformatio available o hipot testers at, a high voltage (up to 4000V AC) is applied across differet parts of the electroic desig i order to stress the dielectrics. Results are displayed i ma or µa - similar to that of leakage curret measuremets. A isulatio resistace test applies a lower DC voltage, typically betwee V DC, across differet parts of the electroic desig. The results are displayed i Mega ohms (MΩ). Isulatio resistace is ormally checked by applyig 500V DC betwee: Iput (live coductors, both phase ad eutral, coected together) ad eclosure (protective earth i class 1). See 7.1. Output (applied parts) ad eclosure (protective earth i class 1). See 7.2. Iput (phase ad eutral) ad output (applied parts) for floatig type applied parts (BF ad CF). See 7.3. The resistace is measured ad the compared with the miimum acceptable value to assess pass or fail coditios, which ca vary greatly depedig o desig ad test voltage variatios. With all measuremets of isulatio resistace, the appliace uder test must have the power switch i the O positio before performig the test otherwise the test voltage does ot pass beyod the mais switch, i which case oly the mais cord will be tested. I additio, appliaces fitted with electroic mais switches or RCD plugs caot be tested i this maer because it is ot possible to close the mais switch (as they require mais to be preset). While the outcome of a 500V DC isulatio test is quick ad safe to do, i most cases it does ot provide a real idicatio of the effectiveess of the isulatio i moder medical devices or the expected leakage values that may be experieced durig ormal or typical operatio. This is due to the icreased use of switch mode power supplies that may idicate very high DC isulatio resistace (>100MΩ), whe measured with AC idicate high leakage. This is due to the greater ifluece of capacitive ad iductive leakage experieced i these devices rather tha resistive leakage as i a heatig elemet. Ifiity readigs are commo whe performig DC isulatio tests ad provide o iformatio as to whether the uit was actually switched o or off. This makes the test results meaigless from a safety poit of view. It is a matter of debate as to whether a 50 MΩ (higher) result is safer tha a 10 MΩ (lower) result, cosiderig the equipmet has bee exposed to a voltage it was ot desiged to operate at. Furthermore, the 50 MΩ (higher) device might have bee desiged to measure 100 MΩ ad has thus lost 50% of its isulatio level. This could lead to higher leakage currets ad usafe coditios. O the plus side, the isulatio resistace test is relatively quick ad easy to perform, which is why it is probably the most widely used. 7.1 Isulatio Resistace EUT to Earth This test is used to verify that the mais parts are adequately isulated from earth (class I) or the eclosure (class II). Figures 12 ad 13 below, show a represetatio of the isulatio test. Figure 12: Isulatio test mais parts to protective earth, class I MΩ Figure 13: Isulatio test mais parts to o-earthed accessible coductive parts, class I ad II MΩ PE I some cases, sesitive electroic devices ad particularly older IT equipmet, which does ot comply with E60950, may be damaged by 500V. However, i practice, this may ot be a sigificat issue as E has bee aroud loger tha most IT equipmet curretly i use. Fially, i some electrical equipmet, compoets coected to the live/eutral coductors for EMC filterig or surge protectio ca sigificatly ifluece the measuremet, idicatig a erroeous failure of the test. PE Durig this test, 500V D.C. is applied betwee the earth pi ad both the live ad eutral pis of the appliace mais supply plug

12 Iovatig Together For both class I ad class II appliaces plug the DUT ito the safety aalyser. Class II equipmet requires a auxiliary lead to be coected to the eclosure of the equipmet. This ca be doe by wrappig the eclosure i alumiium foil ad coectig it to the auxiliary lead via a crocodile clip. 7.2 Isulatio Resistace Applied Parts This test is used to verify that the applied parts are adequately isulated from earth (class I) or the eclosure (class II). This test is applicable to class I ad class II, BF ad CF equipmet oly. Figure 14 ad figure 15 show a represetatio of this isulatio test. Figure 14: Isulatio test applied parts to protective earth, class I PE MΩ 1 2 Figure 15: Isulatio test applied parts to o-earthed accessible coductive parts, class I ad II PE MΩ 1 2 Durig this test, 500V D.C. is applied betwee the earth pi (class I) or the eclosure (class II) ad all the applied parts combied. For both class I ad class II appliaces, coect the patiet coectios or applied parts to the correspodig termials of your safety aalyser. For class I equipmet, plug the mais plug ito the safety aalyser. Class II equipmet requires a auxiliary lead to be coected to the eclosure of the equipmet. This ca be doe by wrappig the eclosure i alumiium foil ad coectig the auxiliary lead via a alligator clip. Figure 16: Isulatio test mais parts to applied parts, class I ad II PE MΩ 1 B BF, CF 2 Durig this test, 500V D.C. is applied betwee all the applied parts combied ad both the live ad eutral pis of the appliace mais supply plug. For both class I ad class II appliaces, coect the patiet coectios or applied parts to the correspodig termials of your safety aalyser ad coect the mais plug to the safety aalyser. 7.4 Isulatio Test Pass Fail imits Although ultimately the pass / fail limits or expected miimum values for this test must be advised by the maufacturer of the equipmet, the IEC does provide a list of commoly accepted values: Figure Class B BF CF Figure 12 I 2 MΩ 2 MΩ 2 MΩ Figure 13 I ad II 7 MΩ 7 MΩ 7 MΩ Figure 14 I ad II 70 MΩ 70 MΩ 70 MΩ Figure 15 I ad II 70 MΩ 70 MΩ 70 MΩ Figure 16 I 2 MΩ 70 MΩ 70 MΩ Figure 16 II 7 MΩ 70 MΩ 70 MΩ 7.3 Isulatio Resistace Applied Parts to Mais This test is used to verify that the applied parts are adequately isulated from the mais parts ad is applicable to class I ad class II, BF ad CF equipmet oly. Figure 16 show a represetatio of the applied parts to mais isulatio test

13 Iovatig Together 8 IEC eakage Measuremets As covered i 1.2, it is the level of electrical curret rather tha level of voltage which is the criteria for safety due to the impact of electrical currets o the huma tissues. Small amouts of curret which are udetectable by sesatio ca have a sigificat impact o our safety. IEC defies two differet kids of leakage curret tests: Equipmet leakage curret - total leakage derivig from the power supply to earth via the applied parts ad eclosure, see 8.2. Applied part leakage curret - leakage curret flowig from a applied part to the eclosure or earth as a result of a exteral voltage o the applied part, see Method Characteristics To esure that a valid leakage measuremet ca be obtaied, the IEC describes the followig methods: Direct eakage - measuremet of leakage curret via a measurig device, placed directly i the path of the leakage curret, see Differetial eakage - measurig the imbalace betwee curret i the ive coductor ad the eutral coductor as a result of leakage curret, see Alterative Method - measuremet of leakage whe mais voltage is both o the live ad eutral wire, see Direct eakage The direct leakage method is idetical to the method used i the IEC stadard; measurig the true leakage through a body model (measurig device) to earth. Beefits: Meas of measurig both AC ad DC leakage curret. Highest accuracy compared to other methods. Potetial leakage through a huma body via measurig device. Direct compariso with measuremets made i accordace with IEC To cosider: The 1kΩ resistor formig the measurig device is iterruptig the low resistace protective earth coductor, thus causig a potetial hazard whe testig faulty equipmet. Secodary earth path(s) could lead to zero curret readigs, see 8.4. A differece i polarity of the live ad eutral coductors might alter the leakage readigs, as such leakage measuremets must be doe i each polarity of mais supply. A T (terre eutral) system is required to esure that the measuremets are doe at maximum live to earth voltage. Ay voltage betwee eutral ad earth might result i a lower readig, potetially passig faulty equipmet, see Differetial Method The differetial leakage method measures the leakage curret as a result of a imbalace i curret betwee the live coductor ad the eutral coductor. The priciple of the differetial leakage measuremet is based o iductio hece, this method is susceptible to exteral magetic fields ad high load currets. As curret passes through the live wire i oe directio, the curret i the atural wire travels i the opposite directio. Each curret produces a magetic field i opposite directios ad directly proportioal to the stregth of curret. See figure 17. Figure 17: Opposite magetic fields i live ad eutral wire ive coductor eutral coductor The curret i the live wire carries both the fuctioal curret ad the leakage curret whereby the curret i the eutral wire cotais oly the fuctioal curret. By subtractig both currets, you ed up with the leakage curret. This is doe i practise by passig both live ad eutral wires through a curret trasformer (CT). The live ad eutral wires act as the primary widigs whereas the CT acts as the secodary widig. The et magetic field i the primary wire is equal to the leakage curret as the eutral field cacels all but the leakage curret from the live wire. The curret beig iducted i the CT is equal to the leakage curret. Potetial secodary earth coectios are icluded i the total measuremet ad as such, the EUT is ot required to be isolated from real Earth. Beefits: The measuremets are ot iflueced by secodary earth coectios. It measures the total equipmet leakage curret. The measurig device (1kΩ resistor) is o loger i series with the earth coductor, providig a low resistace protective earth ad thus is a safer practise compared to the direct method

14 Iovatig Together To cosider: The differetial leakage measuremet is less suitable to accurately measure lower leakage currets (<100µA). The measuremets ca be iflueced by exteral magetic fields or the aalyser s ow iteral magetic fields. The measuremets ca be iflueced by high curret cosumptio of the DUT. The measuremets have limited frequecy respose. A differece i polarity of the live ad eutral coductors might alter the leakage readigs; as such leakage measuremets must be doe i each polarity of mais supply. Both direct ad alterative methods provide higher accuracy ad broader frequecy respose which is required for measurig treds i low leakage coditios Alterative Method The alterative method is i effect similar to a dielectric stregth test at mais potetial, or a isulatio test at AC voltage, usig a curret limited voltage source (test voltage) at mais frequecy. The maximum short circuit curret is limited to 3.5mA through a curret limitig resistor of 66kΩ, see figure 18. The live ad eutral coductors are shorted together ad the test voltage is applied betwee the mais parts ad other parts of the equipmet. The curret limitig resistor of 66kΩ will result i a iteral voltage drop whe a fault curret is flowig. Therefore, the applied test voltage will decrease whe the leakage curret icreases. To reflect testig at mais voltage, the measured leakage curret is scaled i proportio to the actual output voltage. I the example below, a resistace (37kΩ) has bee allocated to a applied part type BF. The total resistace coected to the mais voltage is 103kΩ which results i a fault curret of 2.23mA, measured at a voltage of oly 83V over the applied part. Figure 18: Example of curret limited mais supply durig alterative leakage U=230V 50HZ R I = 66kΩ IEC requires you to scale the measured leakage value up, equivalet to havig 230V over the applied part; (230V / 83V) x 2.2 ma = 6 ma The safety aalyser will display 6mA despite oly measurig 2.23mA. I this approach, it is possible to display high (calculated) leakage currets without actually beig exposed to dagerous currets, makig the alterative leakage curret safe to use whe high fault currets are expected. Beefits: As live ad eutral are combied, the mais polarity has o ifluece. Oly oe measuremet is required. The DUT is discoected from mais thus providig a high level of safety for the test egieer. T-System is ot required due to mais free applicatio. Measuremets are ot iflueced by secodary earth coectios. Measuremets are highly repeatable ad provide a good idicatio of deterioratio i the dielectrics of the medical device uder test. ±2.2 ma 83 V To cosider: Equipmet will ot be activated thus, prevetig the measuremet of actual leakage currets o equipmet with switched circuits. 8.2 Equipmet eakage Equipmet leakage curret - total leakage derivig from the power supply to earth via the applied parts ad eclosure. The equipmet leakage test is applicable to both class I ad II, B, BF ad CF equipmet. eakage measuremets to IEC are doe usig the RMS value istead of the separate AC ad DC values used i the IEC stadard. The IEC specifies three differet methods for measurig the equipmet leakage curret: Direct method Differetial method Alterative method Equipmet eakage Direct Method The direct method is idetical to the method used i the IEC Figure 19 ad figure 20 show a represetatio of the direct method. Figure 19: Equipmet leakage direct - class I PE Figure 20: Equipmet leakage direct class II PE MD () () MD () () 24 25

15 Iovatig Together The DUT must be positioed floatig to avoid secodary earth coectios ifluecig the measurig process. All applied parts (B, BF & CF) ad earthed (e.g. eclosure class I) ad o-earthed accessible coductive parts or o-coductive accessible parts (eclosure class II) are grouped together ad coected to the earth via the 1kΩ measurig device (body model). The 1kΩ measurig device (MD - equivalet to that used i the IEC stadard Curret i µa (RMS) Equipmet leakage direct or differetial method Class I equipmet Class II equipmet (touch curret) see 1.3) is positioed i the leakage retur path to earth. The test is coducted with the protective earth coectio iterrupted, to esure the measuremets are carried out uder the worst possible coditios. As such, ay earth leakage curret will be measured as part of the eclosure (or touch) leakage. Measuremets are doe i both polarities of the icomig mais with the protective earth to the EUT iterrupted. PIED PART B BF CF 100µA For mobile x-ray geerators 2000 µa 100µA 100µA All applied parts (B / BF & CF), earthed (e.g. eclosure class I) ad o-earthed accessible coductive parts or o-coductive accessible parts (eclosure Class II) are grouped together ad coected to earth to allow the differetial circuit to measure the total leakage curret. Ulike the direct method, the differetial method does ot measure the earth coductor via the stadard IEC body model. The MD is part of a differetial curret measuremet betwee the live ad eutral coductors. The frequecy respose of the measuremet shall be similar to the body model used i the IEC Curret i µa (RMS) Equipmet leakage direct or differetial method Class I equipmet Class II equipmet (touch curret) The test is coducted with the protective earth coectio closed for protectio of the user. Measuremets are doe i both polarities of the icomig mais with the protective earth to the EUT iterrupted. ow leakage currets of less tha 75µA are difficult to measure usig the differetial leakage method. As such the differetial leakage method is usuitable whe measurig coductive uearthed parts ad i istaces where leakages are expected to be below 75µA. PIED PART B BF CF 100µA For mobile x-ray geerators 2000 µa 100µA 100µA Equipmet eakage Differetial Method Figure 21 ad figure 22 show a represetatio of the differetial method. Figure 21: Equipmet leakage differetial - class I M Figure 22: Equipmet leakage differetial class II () () M Equipmet eakage Alterative Method This method is i fact similar to a dielectric test betwee the mais parts ad all accessible parts (coductive ad o-coductive) icludig the applied parts coected together. Figure 23 ad figure 24 show a represetatio of the alterative method. Figure 23: Equipmet leakage alterative - class I () PE PE () Potetial secodary earth coectios are icluded i the total measuremet ad as such, the DUT is ot required to be positioed isolated from earth. MD 26 27

16 Iovatig Together Figure 24: Equipmet leakage alterative class II such, mais reversal is ot applicable ad the EUT is ot required to be positioed isolated from earth. betwee the applied part, the eclosure ad earth coectio of the EUT that is coected to real earth. Figure 26: Applied part leakage direct class II MD The test is performed usig a curret limited (3.5mA) mais potetial siusoidal 50Hz sigal (60Hz where this is the mais frequecy). All applied parts, ad earthed (e.g. eclosure class I) ad o-earthed accessible coductive parts or o-coductive accessible parts (eclosure class II) are grouped together ad coected to the mais parts via the 1kΩ measurig device (body model) ad voltage source. The 1kΩ measurig device (equivalet to that used i the IEC stadard see 1.3) is positioed directly after the voltage source. eakage measuremets to IEC are doe usig the RMS value istead of the separate AC ad DC values used i the IEC stadard. The IEC / applied part leakage ca be performed i two differet methods: Direct method Alterative method PE () () MD 1 2 The DUT must be positioed floatig to avoid secodary earth coectios ifluecig the measurig process. As live ad eutral are shorteed, the DUT is ot directly coected to the mais potetial. As Curret i µa (RMS) Equipmet leakage alterative method Class I equipmet Class II equipmet 8.3 Applied Part eakage The applied part leakage test measures the total leakage derivig from the combied patiet coectios withi a applied art to earth ad ay coductive or o coductive parts o the eclosure (either coected or isolated from earth) uder the fault coditio mais o the applied parts. The test is coducted with the protective earth coectio closed to protect the user. PIED PART B BF CF 1000µA For mobile x-ray geerators 5000 µa 1000µA 1000µA All patiet coectios of a sigle fuctio withi a applied part shall be coected together (BF & CF) ad measured oe at the time. Applied parts (ad patiet coectios) are ot part of the measuremet ad shall be left floatig i.e. ot coected to real earth Applied Part eakage Direct Method Figure 25 ad figure 26 show a represetatio of the direct method. Figure 25: Applied part leakage direct - class I PE () () MD 1 2 All floatig type patiet coectios i each applied part (BF & CF) are coected together. Each Idividual applied part is measured i tur ad grouped together with all earthed (e.g. eclosure class I) ad o-earthed accessible coductive parts or o-coductive accessible parts (eclosure class II) ad coected to earth via the 1kΩ measurig device (body model). Applied parts ad patiet coectios ot part of the measuremet shall be left floatig. The 1kΩ measurig device (MD - equivalet to that used i the IEC stadard see 1.3) is positioed betwee the applied part ad voltage source. The applied part leakage test is applicable to floatig type (BF & CF) applied parts oly either class I or II. The test is coducted by applyig a curret limited (3.5mA) mais potetial siusoidal 50Hz sigal (60Hz where this is the mais frequecy) 28 29

17 Iovatig Together The test is coducted with the protective earth coectio closed for protectio of the user. Measuremets are doe i both polarities of the icomig mais with the protective earth to the EUT iterrupted. Warig: This applied part direct leakage test is similar to that of the F-Type leakage test accordig to IEC 60601, usig a equivalet curret limited voltage source to produce the mais potetial. Both sources deped o a curret limitig resistor which could cause a sigificat voltage drop. See figure 18. Ulike the IEC requiremets, the voltage drop caused by the curret limitig resistor is compesated for i the IEC thus, potetially resultig i a higher readig tha the typical IEC F-type test. Please refer to the maufacturer s recommedatios. Figure 28: Applied part leakage alterative class II MD 1 2 All floatig type patiet coectios i each applied part (BF & CF) are coected together. Each idividual applied part is measured i tur ad coected via the 1kΩ measurig device (body model) to the voltage source ad earthed (e.g. eclosure class I) ad o-earthed accessible coductive parts or o-coductive accessible parts (eclosure class II) grouped together. Applied parts ad patiet coectios ot part of the measuremet shall be left floatig. PIED PART Curret i µa (RMS) B BF CF Applied part leakage curret direct method (a.c.) Class I & II /A 5000µA 50µA For defibrillatio paddles class CF /A 100µA As live ad eutral are shorteed, the DUT is ot directly coected to the mais potetial. As such, mais reversal is ot applicable ad the EUT is ot required to be positioed isolated from earth. The 1kΩ measurig device (MD - equivalet to that used i the IEC stadard see 1.3) is positioed betwee the applied part ad voltage source. The test is coducted with the protective earth coectio closed to protect the user Applied Part eakage Alterative Method This method is i fact similar to a dielectric test betwee the applied part, ad all mais parts, EUT earth ad eclosure all coected together. Figures 27 ad 28 show a represetatio of the alterative method. Figure 27: Applied part leakage alterative class I MD 1 2 Curret i µa (RMS) Applied part leakage curret alterative method (a.c.) 8.4 Secodary Earth Problems Due to the fact that electrical currets follow the path of least resistace (much like water does), it is importat to realise that secodary earth path coectios could ifluece the measuremets of leakage currets. PIED PART B BF CF Class I & II /A 5000µA 50µA For defibrillatio paddles class CF /A /A 100µA Secodary coectios are typical with: Equipmet bolted to steel reiforced cocrete floor (e.g. detist chairs, MRI) Equipmet coected to gas or water supply Equipmet that is part of a medical electrical system Equipmet coected to PC / priter 30 31

18 Iovatig Together Compared to the 1kΩ resistace of the body model, a secodary earth path is substatially lower. As such, electrical currets are mostly flowig dow the secodary earth path, away from the safety aalyser, as show i figure 29, which represets a example of a secodary earth coectio via a data cable. Figure 29: Example showig leakage curret flowig away via a secodary earth coectio MD 1000Ω Display <5Ω This will result i a zero readig o the safety aalyser ad could potetially pass a dagerous medical device. I case a secodary earth path exists, the Rigel 288 / will provide the user with a error message as show i figure 30. Figure 30: Secodary earth path error message o Rigel 288 / If the secodary earth path ca t be removed, oe should revert to the differetial leakage method which is capable of measurig the total leakage eve whe a secodary earth path exists. This is because the differetial leakage method does ot rely o a 1kΩ body model. See figure 31. Figure 31: Measurig leakage curret with secodary earth usig differetial method Differetial 8.5 ive to Earth Voltage Durig equipmet leakage measuremets (direct ad differetial), the live to earth voltage ca have a direct impact o the leakage measuremet. I geeral, the smaller the live to earth voltage, the lower the leakage curret to earth (leakage curret flows from a high live to a low earth potetial). Measuremets uder a T (terre eutral) system esure the live to earth voltage is equal to the lie voltage (betwee live ad eutral). This gives the highest possible leakage outcome, see figure 32. If the earth potetial differs from the eutral potetial, the live to earth voltage will be reduced, ad result i a lower leakage value, see figure 33. Figure 32: eakage measuremet o a T system 230V 0V 0V E 230V Figure 33: eakage measuremet o a IT system 230V 100V 0V E 130V eakage curret measuremets o a IT (isolated terre) are limited to isolatio levels of the supply system. I this case, o valid leakage measuremet is possible uless the safety aalyser is able to produce a iteral earth at half the lie voltage, like the Rigel 288. It is also possible to test usig the equipmet leakage usig the alterative method which does ot rely o the icomig mais cofiguratio. Display <5Ω 32 33

19 Iovatig Together The Rigel 288 ad are able to provide a automatic warig to the user i case the supply cofiguratio differs from a T cofiguratio. Figure 34: Automatic mais cofiguratio warig o Rigel 288 / Record Keepig Overall, risk assessmet ad the creatio of risk maagemet files has become a growig feature of routie safety testig decisios, with differet orgaisatios ad departmets drawig-up idividual plas to deal with specific safety hazards. Compariso with previous ad expected test results will therefore allow you to moitor deterioratio of the device uder test ad ca prevet potetial failure before a fault occurs. 9.1 Comparig Data Testig to IEC has reduced the time take to coduct a electrical safety test dow from five miutes to less tha 15 secods v i some cases. What s more, a direct outcome of reducig the amout of idividual tests is that results ca be easily compared agaist previous readigs: tests i differet polarities of the icomig mais rarely result i sigificat differece i readigs, so uder IEC oly a equipmet leakage ad applied part leakage value has to be observed, makig compariso easy ad quick. Comparig data also makes it possible to moitor leakage agaist expected values rather tha the test limits i the IEC Electrical safety testig is oly part of the total service carried out o medical equipmet. Oce the safety is accessed, the fuctioality is verified ad recorded before the equipmet is retured for use o patiets. Rigel Medical has produced a rage of iformative booklets that cover the performace verificatio of; vital sigs moitors, ifusio pumps ad electro surgical geerators. Please visit to request your free copy. To esure proper record keepig is maitaied it is importat to provide a procedure i which data is collected regardig: Ispectio date Visual ispectio Electrical safety Fuctioal testig ext ispectio date The IEC provides a guidelie i collectig such iformatio with the purpose of developig cosistecy i data collectio ad maagemet. By doig so, treds ca be moitored to beefit: Idetifyig commo faults Detect compoet deterioratio (prevetative maiteace) Develop efficiet re-test periods Rigel Medical has developed Med-eBase, a test solutios software package to automate the geeratio of test reports icludig visual ispectio, electrical safety ad performace testig. A example of such test templates is provided i appedix E. Goig forward, determiig the appropriate levels of both electrical ad fuctioal testig will be cetral to the itroductio of cost effective yet reliable prevetative maiteace campaigs. 10 Coclusio Electrical safety testig of medical electroic devices remais a crucial part of the overall safety validatio of medical devices ad requires specialised test equipmet. The IEC stadard will provide; A globally recogised approached to safety testig Developmet tools for safer ad more suitable test protocols Sigificat time savigs durig routie safety testig A easy method to aalyse results agaist previous measuremets A method of record keepig ad maiteace procedures The stregth of IEC is that it allows those who carry out the test to coduct a summary of tests o the iput of medical devices (equipmet leakage) ad o the output of the medical equipmet (applied part leakage). Uiformity i test procedures, time (ad cost) savigs ad a simplified meas of aalysig test data are amog other sigificat beefits vi for those who have made the trasitio to testig i accordace with IEC Time savig associated with IEC will also allow for more time o visual ad fuctioal testig, thus leadig to improved patiet safety. Additioal test setups such as the differetial method ad alterative method give the user a valid measuremet whe circumstaces might ot allow for a valid test measuremet uder IEC (direct method). Whe choosig your future electrical safety aalyser, esure that it ca be used to test i accordace with the IEC requiremets ad secodly that your aalyser will eable you to accurately ad repeatedly produce the results you require Cosideratios ad Recommedatios 1. Esure that the operator of the safety aalyser is properly traied o both the safety aalyser as well as the device uder test to esure that valid measuremets are take ad uderstood, to prevet ueccessary dager durig the safety test

20 Iovatig Together 2. Always esure that the device uder test does ot pose ay dager to the user ad / or people withi the viciity to the safety test. (e.g. movig parts, ope coductors, live compoets, heat etc.). 3. Esure that leakage measuremets are performed whilst the equipmet is i full operatio mode, icludig its sub-systems or compoets, uless the alterative method is beig carried out. 4. Appreciate that secodary earth coectios will lead to ivalid measuremets. Uderstad how to spot secodary earth coectios or beefit from the automatic warig feature o the Rigel 288 / Esure accuracy ad repeatability of leakage measuremet readigs (some maufacturers might specify full scale accuracy which will effect the accuracy of low leakage measuremets). 6. Esure that cotact resistace is take ito accout whe measurig the earth cotiuity at low currets (<8A). Cotact resistace ca ifluece the readigs ad cause uecessary failures of the device uder test. Visit for your free applicatio ote o low curret testig. 7. Whe determiig the correct meas of testig aspecific piece of medical equipmet, esure that the chose safety test procedures are applicable to the device uder test ad are clearly documeted for future use. Rigel Medical offers a rage of test equipmet i lie with the IEC ad IEC requiremets. Please visit our website for a full overview of our product offerig or register olie for our free ewsletter o future product releases ad product iovatios (visit For further questios or commets relatig to this booklet or o the Rigel Medical product offerig, please cotact Joh Backes via at ifo@rigelmedical.com. You ca follow the Seaward Group o: Appedix A Pass / Fail imits of IEC Curret i µa (RMS) Equipmet leakage alterative method Class I equipmet Class II equipmet PIED PART Type B Type BF Type CF 1000µA For mobile x-ray geerators 5000 µa Equipmet leakage direct or differetial method Class I equipmet Class II equipmet (touch curret) 100µA For mobile x-ray geerators 2000 µa Applied part leakage curret alterative method (AC) 1000µA 100µA 1000µA 100µA Class I & II /A 5000µA 50µA For defibrillatio paddles class CF /A /A 100µA Applied part leakage curret direct method (AC) Class I & II /A 5000µA 50µA For defibrillatio paddles class CF /A /A 100µA OTE 1 OTE 2 This IEC stadard does ot provide measurig methods ad allowable values for equipmet producig DC leakage currets. I such a case the maufacturer should give iformatio i accompayig documets. Particular stadards may allow differet values of leakage curret. For a list of particular stadards, please refer to Appedix C

21 Iovatig Together Appedix B IEC Collateral Stadards ( IEC, Appedix C IEC Particulars Stadards ( IEC Geeva, Switzerlad) IEC ed3.1 IEC ed4.0 Medical electrical equipmet - Part 1: Geeral requiremets for basic safety ad essetial performace Medical electrical equipmet - Part 1-2: Geeral requiremets for basic safety ad essetial performace - Collateral Stadard: Electromagetic disturbaces - Requiremets ad tests IEC ed5.0 IEC ed3.0 Medical electrical equipmet - Part 2-2: Particular requiremets for the basic safety ad essetial performace of high frequecy surgical equipmet ad high frequecy surgical accessories Medical electrical equipmet - Part 2-3: Particular requiremets for the basic safety ad essetial performace of short-wave therapy equipmet Medical electrical equipmet - Part 2-4: Particular requiremets for the basic safety ad essetial performace of cardiac defibrillators Medical electrical equipmet - Part 2-5: Particular requiremets for the basic safety ad essetial performace of ultrasoic physiotherapy equipmet Medical electrical equipmet - Part 2-6: Particular requiremets for the basic safety ad essetial performace of microwave therapy equipmet IEC ed2.1 IEC ed3.1 IEC ed2.1 Medical electrical equipmet - Part 1-3: Geeral requiremets for basic safety ad essetial performace - Collateral Stadard: Radiatio protectio i diagostic X-ray equipmet Medical electrical equipmet - Part 1-6: Geeral requiremets for basic safety ad essetial performace - Collateral stadard: Usability Medical electrical equipmet - Part 1-8: Geeral requiremets for basic safety ad essetial performace - Collateral Stadard: Geeral requiremets, tests ad guidace for alarm systems i medical electrical equipmet ad medical electrical systems IEC ed3.0 IEC ed3.0 IEC ed2.0 IEC ed2.0 Medical electrical equipmet - Part 2-8: Particular requiremets for basic safety ad essetial performace of therapeutic X-ray equipmet operatig i the rage 10 kv to 1 MV IEC ed1.1 IEC ed1.1 IEC ed1.0 IEC ed1.0 IEC ed3.1 Medical electrical equipmet - Part 1-9: Geeral requiremets for basic safety ad essetial performace - Collateral Stadard: Requiremets for evirometally coscious desig Medical electrical equipmet - Part 1-10: Geeral requiremets for basic safety ad essetial performace - Collateral Stadard: Requiremets for the developmet of physiologic closed-loop cotrollers Medical electrical equipmet - Part 1-11: Geeral requiremets for basic safety ad essetial performace - Collateral Stadard: Requiremets for medical electrical equipmet ad medical electrical systems used i the home healthcare eviromet Medical electrical equipmet - Part 1-12: Geeral requiremets for basic safety ad essetial performace - Collateral Stadard: Requiremets for medical electrical equipmet ad medical electrical systems iteded for use i the emergecy medical services eviromet Medical electrical equipmet - Part 2-1: Particular requiremets for the basic safety ad essetial performace of electro accelerators i the rage 1 MeV to 50 MeV IEC ed2.0 IEC ed3.0 IEC ed4.0 IEC ed3.0 IEC ed3.0 IEC ed2.0 IEC ed2.0 Medical electrical equipmet - Part 2-10: Particular requiremets for the basic safety ad essetial performace of erve ad muscle stimulators Medical electrical equipmet - Part 2-11: Particular requiremets for the basic safety ad essetial performace of gamma beam therapy equipmet Medical electrical equipmet - Part 2-16: Particular requiremets for basic safety ad essetial performace of haemodialysis, haemodiafiltratio ad haemofiltratio equipmet Medical electrical equipmet - Part 2-17: Particular requiremets for the basic safety ad essetial performace of automatically-cotrolled brachytherapy afterloadig equipmet Medical electrical equipmet - Part 2-18: Particular requiremets for the basic safety ad essetial performace of edoscopic equipmet Medical electrical equipmet - Part 2-19: Particular requiremets for the basic safety ad essetial performace of ifat icubators Medical electrical equipmet - Part 2-20: Particular requiremets for the basic safety ad essetial performace of ifat trasport icubators Medical electrical equipmet - Part 2-21: Particular requiremets for the basic safety ad essetial performace of ifat radiat warmers IEC ed2.0 IEC ed3.1 Medical electrical equipmet - Part 2-22: Particular requiremets for basic safety ad essetial performace of surgical, cosmetic, therapeutic ad diagostic laser equipmet IEC ed3.0 Medical electrical equipmet - Part 2-23: Particular requiremets for the basic safety ad essetial performace of trascutaeous partial pressure moitorig equipmet 38 39

22 Iovatig Together IEC ed2.0 Medical electrical equipmet - Part 2-24: Particular requiremets for the basic safety ad essetial performace of ifusio pumps ad cotrollers IEC ed2.0 Medical electrical equipmet - Part 2-49: Particular requiremets for the basic safety ad essetial performace of multifuctio patiet moitorig equipmet IEC ed2.0 Medical electrical equipmet - Part 2-25: Particular requiremets for the basic safety ad essetial performace of electrocardiographs IEC ed2.0 Medical electrical equipmet - Part 2-50: Particular requiremets for the basic safety ad essetial performace of ifat phototherapy equipmet IEC ed3.0 Medical electrical equipmet - Part 2-26: Particular requiremets for the basic safety ad essetial performace of electroecephalographs IEC ed1.0 Medical electrical equipmet - Part 2-52: Particular requiremets for the basic safety ad essetial performace of medical beds IEC ed3.0 Medical electrical equipmet - Part 2-27: Particular requiremets for the basic safety ad essetial performace of electrocardiographic moitorig equipmet IEC ed1.0 Medical electrical equipmet - Part 2-54: Particular requiremets for the basic safety ad essetial performace of X-ray equipmet for radiography ad radioscopy IEC ed2.0 IEC ed3.0 IEC ed2.1 IEC ed3.1 IEC ed3.0 IEC ed2.0 IEC ed2.0 IEC ed2.0 IEC ed1.0 IEC ed2.1 Medical electrical equipmet - Part 2-28: Particular requiremets for the basic safety ad essetial performace of X-ray tube assemblies for medical diagosis Medical electrical equipmet - Part 2-29: Particular requiremets for the basic safety ad essetial performace of radiotherapy simulators Medical electrical equipmet - Part 2-31: Particular requiremets for the basic safety ad essetial performace of exteral cardiac pacemakers with iteral power source Medical electrical equipmet - Part 2-33: Particular requiremets for the basic safety ad essetial performace of magetic resoace equipmet for medical diagosis Medical electrical equipmet - Part 2-34: Particular requiremets for the basic safety ad essetial performace of ivasive blood pressure moitorig equipmet Medical electrical equipmet - Part 2-36: Particular requiremets for the basic safety ad essetial performace of equipmet for extra-corporeally iduced lithotripsy Medical electrical equipmet - Part 2-37: Particular requiremets for the basic safety ad essetial performace of ultrasoic medical diagostic ad moitorig equipmet Medical electrical equipmet - Part 2-39: Particular requiremets for basic safety ad essetial performace of peritoeal dialysis equipmet Medical electrical equipmet - Part 2-40: Particular requiremets for the safety of electromyography ad evoked respose equipmet Medical electrical equipmet - Part 2-41: Particular requiremets for the basic safety ad essetial performace of surgical lumiaires ad lumiaires for diagosis IEC ed1.0 IEC ed1.0 IEC ed1.0 IEC ed1.0 IEC ed1.0 IEC ed1.0 IEC ed1.0 Appedix D Patiet Eviromet Medical electrical equipmet - Part 2-57: Particular requiremets for the basic safety ad essetial performace of o-laser light source equipmet iteded for therapeutic, diagostic, moitorig ad cosmetic/aesthetic use Medical electrical equipmet - Part 2-62: Particular requiremets for the basic safety ad essetial performace of high itesity therapeutic ultrasoud (HITU) equipmet Medical electrical equipmet - Part 2-63: Particular requiremets for the basic safety ad essetial performace of detal extra-oral X-ray equipmet Medical electrical equipmet - Part 2-64: Particular requiremets for the basic safety ad essetial performace of light io beam medical electrical equipmet Medical electrical equipmet - Part 2-65: Particular requiremets for the basic safety ad essetial performace of detal itra-oral X-ray equipmet Medical electrical equipmet - Part 2-66: Particular requiremets for the basic safety ad essetial performace of hearig istrumets ad hearig istrumet systems Electrical medical equipmet - Part 2-68: Particular requiremets for the basic safety ad essetial performace of X-ray-based image-guided radiotherapy equipmet for use with electro accelerators, light io beam therapy equipmet ad radiouclide beam therapy equipmet IEC ed2.0 Medical electrical equipmet - Part 2-43: Particular requiremets for the basic safety ad essetial performace of X-ray equipmet for itervetioal procedures IEC ed3.1 IEC ed3.0 Medical electrical equipmet - Part 2-44: Particular requiremets for the basic safety ad essetial performace of X-ray equipmet for computed tomography Medical electrical equipmet - Part 2-45: Particular requiremets for basic safety ad essetial performace of mammographic X-ray equipmet ad mammographic stereotactic devices m IEC ed2.0 IEC ed2.0 Medical electrical equipmet - Part 2-46: Particular requiremets for basic safety ad essetial performace of operatig tables Medical electrical equipmet - Part 2-47: Particular requiremets for the basic safety ad essetial performace of ambulatory electrocardiographic systems 1.5 m 1.5 m 40 41

23 Iovatig Together Appedix E Example documetatio template Appedix E Example documetatio template Testig orgaisatio: ame of testig perso: Resposible orgaisatio: Equipmet: Test before puttig ito service (referece value) Recurret Test Test after repair Type: Productio o./serial r.: Maufacturer: Class of protectio: I II Battery 1) Applied part type: 0 B BF CF Mais coectio: PIE PS DPS Accessories: Test: Measuremet equipmet: Visual ispectio: Measuremets: Protective earth resistace Equipmet leakage curret (accordig to Figure...) Patiet leakage curret (accordig to Figure...) Isulatio resistece (accordig to Figure...) ID umber: Measured value Ω ma ma MΩ Complies Yes o i Effects of Electrical Curret o Heart Rhythm, HOCHBERG, HOWARD M.1971 ii Harm is a defied term i ISO 14971:2000 as physical ijury or damage to the health of people or aimals, or damage to property or the Eviromet iii I IEC 60601, safe levels of curret are defied as 10µA AC / DC for CF applied parts ad 100µA AC / 10µ DC for B / BF applied parts ad touch curret. Earth leakage limits are higher at RMS for equipmet with coductive accessible parts that may become live uder a fault coditio ad 5000µA RMS for earthed devices with o coductive accessible parts. Uder fault coditios, higher values are allowed. iv v A free applicatio ote o this subject is available at; Comparig the tests of a 12 lead ECG (CF) moitor which requires 290 AC ad DC leakage readigs uder IEC (excludig SIP-SOP) ad oly 4 leakage readigs i IEC vi Iformatio gathered by Rigel Medical durig over 40 iteratioal semiars o IEC Fuctioal Test (parameters tested): Deficiecy / ote: Overall Assessmet: o safety or fuctioal deficiecies were detected o direct risk, deficiecies detected may be corrected o short term Equipmet shall be take out of operatio util deficiecies are corrected Equipmet does ot comply Modificatios / Exchage of compoets / Takig out of service is recommeded ext recurret test ecessary i 6 / 12 / 24 / 36 moths ame: 1) PIE PS DPS Date/Sigature: Permaet istalled equipmet o-detachabe POWER SUPPY CORD DETACHABE POWER SUPPY CORD 42 43

24 Electrical Safety Aalysers Rigel 288+ ad Electrical Safety Aalysers The Rigel rage of battery powered electrical safety testers offers a accurate ad fast solutio for meetig iteratioal ad local safety stadards. These uiquely desiged testers icorporate a ucompromised list of test features withi oe compact uit, icludig automatic leakage, earth bod ad isulatio testig to iteratioal ad local stadards icludig IEC 62353, ad FPA-99. A itegrated keyboard eables detailed equipmet data to be stored o-board alogside electrical safety test results; providig complete traceability of results. With a choice from 2 up to 10 idividual patiet leakage circuits, we have the right solutio to test ay medical equipmet, from beds to multi-parameter moitors i a sigle test routie. A combied high ad low earth bod test curret esures accurate resistace measuremets are made ad that poor mechaical coectios ca be idetified. Automatic warigs of icorrect test setups help to avoid false readigs, for example whe secodary earth paths are preset, providig cofidece i results ad eablig improved patiet safety. Use the Rigel safety aalysers with Med-eBase software to ulock ehaced customisatio features, create bespoke test templates ad improve traceability ad maagemet of test results. Fuctios available uder battery power Tests Earth bod Isulatio Data trasfer Dowload results Upload sequeces, templates ad assets Scaig Barcode Pritig Results Pass/Fail labels Settig up Test sequeces Test codes Asset trace variables site, locatio etc Bluetooth System cofiguratio Viewig results/data t Features IEC 60601* leakage IEC leakage IEC leakage Applied Parts Max earthbod curret Poit to poit measuremet Isulatio test IEC lead test Maual mode Automatic mode Custom test sequecig Battery operatio Data storage Data etry Barcode scaig PC dowload Secodary earth warig ie voltage check Direct prit facility Weight (kg) 10 30A** ABCD < A** ABCD <1.7 Product Beefits: Full compliace Have peace of mid whe it comes to havig to comply with (iteratioal) stadards ad recommedatios icludig IEC ad leakage tests i accordace with IEC 60601, FPA, AAMI ad AS/Z Battery powered Save valuable time by usig stadard AA batteries to keep your tester operatioal i betwee tests whe movig from oe mais socket to the ext. Automated testig Save time ad moey by automatig test procedures, ad be assured that test procedures are performed i a cosistet maer. Electroic data storage Reduce the risk of data capture errors or maipulatio ad speed-up admiistratio with automated data storage. Automatic test verificatio Get the correct results first time ad avoid time-cosumig re-tests with Rigel s uique ad automated verificatio of secodary earth paths ad icomig mais cofiguratios. Uique earth bod techology Rigel s uique high curret, low eergy earth bod test, gives accurate ad precise readigs, savig time ad uecessary replacemet of good mais cables. Smallest ad most compact Reduce the burde of carryig multiple istrumets from site to site by usig the most compact electrical safety aalyser o the market. Sca QR code to fid out more * icludig all local derivitives (AAMI, FPA, AS/Z, VDE) ** usig high curret low eergy method 44 45

25 Rigel Medical, Bracke Hill, South West Idustrial Estate, Peterlee, Couty Durham, SR8 2SW Uited Kigdom Part of Tel: +44 (0) Fax: +44 (0) Web: rigelmedical.com Versio 1.0_2015