PSNet
The announcement of the availability of the update to IEC 60990, shown below, has been circulating for a short time now. As Convenor (Chairman) of this committee I had not generally circulated it to the PSNet since it is not a product standard but a basic standard to be used by product standards writing committees. As is usually the case, the information in basic standards is excerpted or summarized in product standards. Two IEC committees have been integrating this information into their product standards for some time; IEC TC66/IEC 61010 (and the 1010 derivitive EN, CSA and UL standards) and IEC TC74/IEC 60950 (and the 950 derivitive EN, CSA and UL standards). The implementation of these requirements into these two standards families is done in a slightly different way and neither is a full copy of the IEC 60990 set of recommended requirements. The certification requirements for the products are contained in the end product standard. We expect to see ongoing changes to the measurement of touch current at the product level to accommodate the introduction of new technology which changes touch current and exposes the user to this aspect of electric shock in some new way. If you are a designer of test equipment making this measurement or want to see the latest information regarding the measurement of touch current you should buy a copy of this standard. This new standard is now available from the IEC - either thru their website or paper copy. INFORMATION TECHNOLOGY / ELECTRICAL AND MAGNETIC MEASUREMENTS "IEC 60990 (1999-08) - Methods of measurement of touch current and protective conductor current" Defines measurement methods for d.c. or a.c. of sinusoidal or non-sinusoidal waveform, which could flow through the human body, andcurrent flowing through a protective conductor. The measuring methods recommended for TOUCH CURRENT are based upon the possible effects of current flowing through a human body. In this standard, measurements of current through networks representing the impedance of the human body are referred to as measurements of TOUCH CURRENT. These networks are not necessarily valid for the bodies of animals. The basic safety publication is primarily intended for use by technical committees in the preparation of standards in accordance with the principles laid down in IEC Guide 104 and ISO/IEC Guide 51. It is not intended for use by manufacturers or certification bodies. It has the status of a basic safety publication in accordance with IEC Guide 104. Milton Cox, Secretary of IEC Technical Committee 74 (Safety and energy efficiency of IT equipment), provides the following information on this new publication: "The second edition of IEC 60990 has been issued as an International Standard replacing the first edition issued as a technical report in 1990. Input from users of the technical report has resulted in the following principle changes included in the second edition: - provision of an earthing alternative for testing to accommodate some test situations. - provision of a more detailed description of the design and calibration of the measurement network - as a result the component tolerances have been deleted from the network diagrams. With the publication of the second edition, it is expected the use of the precise terms 'touch current' and 'protective conductor current' and the measurement techniques will be used more extensively by technical committees." ICS Codes: 17.220, 35.020 - TC 74 - 109 pp. - CHF 153.00 - - - - - Peter E Perkins Principal Product Safety Consultant Tigard, ORe 97281-3427 +1/503/452-1201 phone/fax p.perk...@ieee.org email visit our website: http://ourworld.compuserve.com/homepages/peperkins - - - - - --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).