>From IEC 60950, third edition, clause 1.5.7.2 Bridging resistors: "It is permitted to bridge double or reinforced insulation by two resistors in series. They shall each comply with the requirements of 2.10.3 and 2.10.4 (clearance and creepage) between their terminations for the total working voltage across the pair and shall have the same nominal resistance value."
Patty Elliot Qualcomm, Inc. [email protected] At 02:05 PM 9/16/99 -0700, Jim Eichner wrote: > >Hi everyone: Is there a standard interpretation (e.g. in EN60950) that >allows or disallows the bridging of a Reinforced isolation boundary by >resistors? This stretches the term "isolation" a bit, but my feeling is >that isolation really involves dielectric withstand and limitation of >leakage current, both of which can be provided by resistors. If there >is disagreement with that, I'm dead right away. > >So assuming the idea isn't dead right off the bat, here are some ideas >off the top of my head: > >- obviously there would have to be 2 or more in series, to meet the >single fault requirement >- the total resistance would have to be sufficient to limit the current >during hipot testing to a value that the hipot instrument can handle >(say 5mA at 3000V, so 600k ohms) and a value that is acceptable to be >considered >- each resistance would have to be sufficient so that, with the other >one shorted out, the leakage current between the two circuits would be >limited to non-shock-hazardous levels given the working voltage in the 2 >circuits > >Any comments or previous interpretations on this, anyone? > >Thanks in advance, > > >Jim Eichner >> Senior Regulatory Compliance Engineer >Statpower Technologies Corporation >[email protected] >http://www.statpower.com >Any opinions expressed are those of my invisible friend, who really >exists. Honest. > > > >--------- >This message is coming from the emc-pstc discussion list. >To cancel your subscription, send mail to [email protected] >with the single line: "unsubscribe emc-pstc" (without the >quotes). For help, send mail to [email protected], >[email protected], [email protected], or >[email protected] (the list administrators). > >
