Mr. Peruzzi, With the exception of certain ECMA safety standards and the IEC safety standard for power supplies (61204), I am not aware of any IEC/harmonized safety standards that contain special clauses for the consideration of the power supply's performance and construction as a special type of component; i.e., there are no "a component power supply shall ..." statements.
In fact, most safety standards will have a statement in the scope that says that if the power supply is not installed within the end-use system, it is not covered; e.g., "power supply systems which are not an integral part of the equipment...". AND "Where a separate power supply (such as those containing transformer and dc conversion in a separate package and feeding dc directly into the equipment) is required, the supply shall be identified in the instructions for use as: 1) part of the equipment (the requirements of this standard apply to it also) OR 2) part of an ME System (meaning the supply can comply to another IEC standard but with appropriate isolation in the ME equipment). The supply must be specified in adequate detail to assure continuing compliance to this standard." The 3d ed of 60601-1 says this about power supplies: 4.8 *Power supply 4.8.1 Source of power for ME EQUIPMENT ME EQUIPMENT shall either be powered by an INTERNAL ELECTRICAL POWER SOURCE, be specified for connection to a separate power supply, or be suitable for connection to a SUPPLY MAINS. 5.5 Supply voltages, type of current, nature of supply, frequency a) Where test results are influenced by deviations of the supply voltage >from its RATED value, the effect of such deviations shall be taken into account. The supply voltage during tests shall be according to 4.8 or according to that specified by the MANUFACTURER, whichever is least favourable. b) ME EQUIPMENT for a.c. only shall be tested with a.c. at RATED frequency (if marked) ± 1 Hz between 0 and 100 Hz and ± 1 % above 100 Hz. ME EQUIPMENT marked with a RATED frequency range shall be tested at the least favourable frequency within that range. c) ME EQUIPMENT designed for more than one RATED voltage, or for both a.c. and d.c., shall be tested in conditions (described in 5.4) related to the least favourable voltage and nature of supply, for example, number of phases (except for single-phase supply) and type of current. It may be necessary to perform some tests more than once in order to establish which supply configuration is least favourable. 16.3 *Power supply If ME EQUIPMENT is intended to receive its power from other equipment in an ME SYSTEM, the instructions for use shall specify such other equipment sufficiently to ensure compliance with the requirements of this standard (see 4.8.1, 5.5 g) and 7.10.2.3). Most SMPS are certified as 'components', so you will probably be limited to applying the requirements for components of the end-use standard. And this is why the conditions of acceptability and the Type Test conditions for the SMPS are so very very important. As the regulatory honcho for your company, you must insist the the vendor provide a CB test report for the unit. And you must study and understand whether the vendor's type test conditions can apply to both normal and abnormal operating conditions of your end-use box. Because the new IEC medical standard has complex risk-analysis requirements, you will need a direct safety contact at your power supply vendor. No one can hand this to you in neatly packaged standard that also has the added bonus of an additional clause explaining the meaning of life (this was, in fact, clearly defined by Douglas Adams...). Ultimately, I can only offer this advise - Root Beer and Cheetos are very effective compliance-requirement analysis tools. luck, Brian > -----Original Message----- > From: [email protected] [mailto:[email protected]]On Behalf Of Paolo > Peruzzi > Sent: Friday, March 23, 2007 1:32 AM > To: [email protected] > Subject: RE: SMPS test according to IEC 60601-1 > > > Brian, > Could you please give me ONE example of a specific > requirement on a POWER > SUPPLY (not on a single component) in IEC 60601-1? > > Thanks, > Paolo Peruzzi > > ---------- Original Message ----------- > From: "Brian O'Connell" <[email protected]> > To: <[email protected]> > Sent: Thu, 22 Mar 2007 08:10:13 -0800 > Subject: RE: SMPS test according to IEC 60601-1 > > > Although, the 3d edition of IEC 60601-1 'appears' to relax test > > requirements for a component P.S. (and explicityly allows > the use of > > I.T. approved units), and I recommend that you avoid the temptation > > to reduce these tests to that of 'transformer'. > > > > My employer makes many custom and off-the-shelf power > supply models that > > are certified to medical standards, and we encourage our > customers to > > repeat certain SFC tests and abnormal operating conditions in the > > end-use installation. > > > > Also, try to get a copy of the CB Test Report. Carefully review the > > tests, test conditions, and what failed as a result of the > test. The > > performance of the P.S. during abnormal operating conditions should > > drive the conditions of acceptability for the end-use installation. > > > > Requirements for SFC test and abnormal operating conditions will be > > dependent on the affect of the end-unit installation has on > the component > > power supply. And yes there are, in fact, specific requirements in > > 601-1 that would apply to a component power supply. Read the > > standard again. No, again. > > > > luck, > > Brian > > > > > -----Original Message----- > > > From: [email protected] [mailto:[email protected]]On > Behalf Of Paolo > > > Peruzzi > > > Sent: Thursday, March 22, 2007 7:25 AM > > > To: [email protected] > > > Subject: SMPS test according to IEC 60601-1 > > > > > > Dear group, > > > > > > I would like to gather some opinions about safety tests on > > > switch mode power > > > supplies within medical devices, according to IEC 60601-1. > > > My question arises because a test house technician told me he > > > used to test > > > power supplies as they were transformers, for what concerns > > > short circuit > > > and overload tests, on each dc output. > > > I couldn't find such requirements for power supplies in the > > > standard (I > > > couldn't find any!!!), but I think it would be at least wise > > > to do these > > > tests. > > > Do you think they should be included as single fault > > > condition tests, even > > > if not mentioned? > > > Any other thoughts? > > > > > > Thanks, > > > > > > Paolo Peruzzi - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. 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