John, I just realized that Amendment 1 to IEC1010 added a new section (14.7) to cover mains transformers "not tested as part of the equipment." It also changes the wording in section 4.4.2.6 for transformers that are "tested as part of the equipment." The overload tests in 14.7 and 4.4.2.6 are more extensive than the ones specified in Annex C of IEC950. I have to retract my statement that transformers that meet IEC950 will almost certainly meet IEC1010. You wouldn't know for sure until you did the additional overload tests called out in IEC1010. Still, there is nothing in IEC1010 that says transformers "built into the equipment" have to meet IEC742. An IEC950 transformer that is also tested to meet IEC1010 section 14.7 or 4.4.2.6 would be acceptable.
Regards, Mike Rains >---------- >From: Rains,Mike[SMTP:[email protected]] >Sent: Wednesday, February 05, 1997 1:22PM >To: [email protected] >Cc: '[email protected]' >Subject: RE: Transformer Approvals > >John, > >My understanding of IEC1010 is that IEC742 only applies to transformers >that are stand-alone (not built in). Transformers that are built-in need >only comply with the requirements in IEC1010. While there is no specific >section for transformers in IEC1010, there is a section for doing short >circuit tests on secondary windings (4.4.2.6). The transformers would >also have to meet the applicable spacing requirements in Annex D and the >dielectric strength requirements in 6.8 and other construction >requirements as they apply (e.g., double insulation, etc.). Regarding >IEC950, I can't think of an instance where a transformer that met IEC950 >requirements would not also meet or exceed the IEC1010 requirements. >There may be some conditions where it wouldn't, but I haven't run into >one yet. I would challenge the interpretation that you received. > >Regards, >Mike Rains >Foxboro Co. >>---------- >>From: [email protected][SMTP:[email protected]] >>Sent: Wednesday, February 05, 1997 7:58AM >>To: [email protected] >>Cc: [email protected] >>Subject: Re: Transformer Approvals >> >>Just wanted to thank you for your explanation. In this case, the >>transformers are built in to the instrument, behind a panel that >>requires a 'tool' (key locked) to gain entry. I did have some >>confusion about this, because as you indicated, IEC 1010 doesn't >>specify a specific transformer standard to follow. >> >>I guess that we now have (2) choices - >> >>1. Purchase and install transformers that have IEC 742 certification. >> - or - >>2. Purchase copies of both IEC 742 and IEC 950 and evaluate >>whether the IEC 950 certified transformers meet the requirements >>of IEC 742 for our equipment. This *may* involve additional testing >>and would most certainly be more time consuming. Potentially it could >>be less costly in the long run, as domestic manufacturers of general >>purpose transformers seem to only be offering products with IEC 950 >>compliance. To get a transformer with IEC 742 compliance, I'd have >>to switch from using Signal Transformer to Legrand or some other >>European company. >> >>----------------------------------------- >>John Bielot >>Canberra Industries >>Applied Systems Division >>e-mail: [email protected] >>----------------------------------------- >>> >>>On 04-Feb-97 you wrote >>> >>> >>>Hello from San Diego: >>> >>> >>>IEC 742 (aka EN 60742) applies to transformers in general and >>>stand-alone transformers in particular. >>> >>>IEC 742 contains some additional requirements for stand-alone >>>transformers compared to those in IEC 950 (aka EN 60950). >>> >>>Unfortunately, IEC 1010 (aka EN 61010) does not contain specific >>>transformer requirements, so IEC 742 can be invoked if the test >>>house so chooses. >>> >>>If your transformer is built-in, then I believe a transformer >>>complying with IEC 950 also complies with IEC 742. >>> >>>It may be that the test house is simply saying that an IEC 950 >>>certified transformer, by definition (not by test), does not >>>comply with IEC 742. In other words, they cannot accept, carte >>>blanche, the IEC 950 certification as being applicable to >>>IEC 1010, whereas they could accept IEC 742 certification. >>> >>>This may mean that the test house will need to conduct tests to >>>demonstrate compliance with IEC 1010. >>> >>> >>>Best regards, >>>Rich >>> >>> >>> >>>------------------------------------------------------------- >> >Richard Nute Quality Department >> >Hewlett-Packard Company Product Regulations Group >> >San Diego Division (SDD) Tel : 619 655 3329 >> >16399 West Bernardo Drive FAX : 619 655 4979 >> >San Diego, California 92127 e-mail: [email protected] >>>------------------------------------------------------------- >> >> >
