Article View: sci.electronics.design
Article #877Re: An unusual Oscilloscope phenomenon
From: Joerg
Date: Tue, 07 Jul 2009 21:03
Date: Tue, 07 Jul 2009 21:03
50 lines
3617 bytes
3617 bytes
Michael A. Terrell wrote: > terryc wrote: >> On Mon, 06 Jul 2009 17:38:19 -0700, Joerg wrote: >> >>> terryc wrote: >>>> On Mon, 06 Jul 2009 12:05:37 -0700, Joerg wrote: >>>> >>>> >>>> >>>>> In a welding environment 800V may not be good enough. >>>> Which "welding" environments did you have in mind? >>>> >>>> >>> The usual. >100 amps, electrodes touching, arcing, getting stuck once in >>> a while, thick cables floating around the room, ground potential of >>> equipment bouncing, and so on. I once told someone to get his ham radio >>> gear out before we start welding a broken gate. "Nah, this stuff is >>> tough" ... "Better get it outta here" ... "No, really, it's ok, just get >>> cracking on the gate" ... "Ok then" ... bzzt, bzzt, bzzzzzzzzzzt ... >>> beep ... *PHUT* >> Umm, have you ever put a volt meter across the cables? >> I was under the impression that that stuff matched the telephone and was >> in the vicinity of 40volts. >> >> I politely suggest that if it was around 800volts, then black and crispy >> would be a welder who made the wrong circuit. >> >> Hint, it is the current that causes the field. > Hint: There's lots of inductances involved, wanted ones as well as undesired ones. Inductance -> current -> current suddenly stops -> inductance says "I don't think so!" -> tsssk ... *PHUT* > > Its the collapsing field that generates the HV spikes that can, and > does knock careless welders on their asses. > And mains connected power supplies. That's what croaked in the radio. The spikes on a mains circuit of sufficient length (and thus impedance) look rather terrifying. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
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X-Google-Thread: a5a6238865,2fb4482ba391e6 X-Google-Attributes: gida5a6238865,public,usenet X-Google-NewGroupId: yes X-Google-Language: ENGLISH,ASCII-7-bit Path: arc1-ca.pugleaf.net!g2news2.google.com!news1.google.com!border1.nntp.dca.giganews.com!nntp.giganews.com!newsfeed00.sul.t-online.de!t-online.de!newsfeed.r-kom.de!fu-berlin.de!uni-berlin.de!individual.net!not-for-mail From: Joerg <invalid@invalid.invalid> Newsgroups: sci.electronics.design,aus.electronics Subject: Re: An unusual Oscilloscope phenomenon Date: Tue, 07 Jul 2009 14:03:41 -0700 Organization: Consultant Lines: 50 Message-ID: <7bhrhiF23hnm7U1@mid.individual.net> References: <h8B0m.53620$FI5.3564@newsfe12.iad> <C5D0m.1651$vO4.300@flpi145.ffdc.sbc.com> <n41645hvv4ia1uqa1cnbriilvg4vg1td2a@4ax.com> <z_udncS2Q9vvJd7XnZ2dnUVZ_odi4p2d@supernews.com> <u4k745pit2pm2qep1k9apmcgda9ugb1uqe@4ax.com> <pan.2009.06.30.18.25.22.512231@example.net> <q2lk45pnpbb3esgo2bi6pp2f85p977qbjb@4ax.com> <7av4ckF2168qeU4@mid.individual.net> <sjnk459n6lgmicl8c1dflfutbghqp20tfp@4ax.com> <4a4bab66.2595149687@news.planet.nl> <7b1sftF1sbgmcU1@mid.individual.net> <4a4bdde5.2608076625@news.planet.nl> <7b2an2F1vorf3U1@mid.individual.net> <4a4e83ad.2781589312@news.planet.nl> <7bf082F232f2kU1@mid.individual.net> <4a527fd4$0$68552$c30e37c6@pit-reader.telstra.net> <7bfjnvF22lu8vU1@mid.individual.net> <4a533ccd$0$68552$c30e37c6@pit-reader.telstra.net> <4A533FE6.9E275BA8@earthlink.net> Reply-To: news@analogconsultants.com Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Trace: individual.net FOdV/sJW2kjeKtY87C5leABmuAFxJ1gnWK0joZkU3djoxVg//D Cancel-Lock: sha1:bJmD5OK9wyWLagAwr82/B1VOqqg= User-Agent: Thunderbird 2.0.0.6 (Windows/20070728) In-Reply-To: <4A533FE6.9E275BA8@earthlink.net>