Perhaps "resultant current" or "net RMS current" would have been better than "vector sum". A vector sum implies to me, drawing the vectors and adding them graphically, or adding their real & imag rectangular components.
If I recall correctly, the RMS (effective) value is also the square-root of the algebraic sum of the squares of the magnitudes of the harmonic terms. I understand that these RCCB devices do this sum, presumably by a resultant flux in a magnetic circuit. ====================================== Ralph McDiarmid, ASc Compliance Engineering Group Xantrex Technology Inc. From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of John Woodgate Sent: Friday, February 03, 2006 11:35 AM To: emc-p...@ieee.org Subject: Re: Definition of Residual Current In message <de87437fe365cb458c265ea3d73b6f1d013da...@xbc-mail1.xantrex.com>, dated Fri, 3 Feb 2006, Jim Eichner <jim.eich...@xantrex.com> writes >I am working on a standard for which a definition of Residual Current >is needed. I don't own any other standard that defines it, and I don't >subscribe to the IEC electrotechnical vocabulary (perhaps I should). At >any rate, I could use some help please. > >1. Does anyone have an official definition for me? Please state your >source. There are several in the IEV, but see below. Some apply only to 3-phase supplies without a neutral conductor. > >2. According to the standard for RCCB's, IEC 61008-1, here's the >definition (translated from German to English by a colleague, so >perhaps not verbatim from the English version of the standard): > >Residual current: "Vector sum of the actual values of the currents >flowing in the main circuit of an RCCB" > >That seems like a pretty poor definition to me, as it is circular and a >bit vague It's close to the IEV definition 442-05-19: r.m.s. value of the vector sum of the currents flowing through the main circuit of the residual current device But yes, your 'translator' had better not give up the day job. (;-) >(I'm guessing "main circuit" should read "mains circuit" but still that >could be interpreted to include the earth wire in which case it's >incorrect). No, 'main circuit' excludes the earth wire. > >I think the definition does not need to and should not make any >reference to an RCCB, because residual current exists whether or not an >RCCB is used, and using RCCB in the definition just requires a >definition of RCCB, leading back to a need to define what Residual >Current is. > >I think the definition should be something like this: > >"Residual Current: The vector sum of the currents in each phase and >neutral (if applicable), OK so far, and similar to another, but less satisfactory, IEV definition, which says 'algebraic' instead of 'vector' and is thus not really correct. >which if non-zero indicates that current is returning to the source via >a path other than the current-carrying conductors, which therefore >indicates a potential shock hazard." Such words of explanation are not permitted in an IEV definition. > -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk 2006 is YMMVI- Your mileage may vary immoderately. John Woodgate - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.org Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.org Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
