Brian and all: I have never been to a Wisconsin farm but I recognize a few key symptoms. The dairy farms I have been to have three pole pigs hanging on the power pole. Three phase power is necessary for many pumps and other heavy machinery. The common connection is delta wye.
Many of the modern power control/conversion systems, such as speed controls, SCR power supplies, or power factor correction systems generate high harmonic currents. It is possible to get neutral currents exceeding the line current. The reference to 180 hertz components in the second document is symptomatic. Too bad the power company can't do a better job of defending their case. Fred Townsend Brian O'Connell wrote: >Good People, > >The Wisconsin Supreme Court thinks that 'stray' voltage from the power >grid is causing livestock problems. Note these links to this issue. > >http://www.thonline.com/store/view.cfm?id=JiZNUz7AxXXkdICgz3Dz3D > >http://www.strayvoltage.org/stories/index.php3?Story=20010812_researchers. >inc > >My (probably stupid) questions: > >1. As most ground-loop current problems are caused when neutral is >grounded at multiple points, why is the power utility blamed for an >end-user wiring error ? > >2. The result of 'stray' voltage would seem to be excessive ground-wire >current. Why is a protection device not interrupting this fault current ? > >3. The multiple instances of power distribution transformers should >isolate, and therefore interrupt current leakage paths, because the >customer's (secondary-side) neutral is grounded at a single point for each >customer. So the only excessive (continuous) fault current should result >from the customer stringing extra grounds to the distribution >transformer's case. So what is the leakage path and why is a sufficient >potential developed that can cause this continuous fault current ? > >luck, >Brian > >- >---------------------------------------------------------------- >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 [email protected] > >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 [email protected] > Mike Cantwell [email protected] > >For policy questions, send mail to: > > Jim Bacher: [email protected] > David Heald: [email protected] > >All emc-pstc postings are archived and searchable on the web at: > > http://www.ieeecommunities.org/emc-pstc > >-------------------------------------- >Text inserted by Platinum 2007: > > This message has NOT been classified as spam. If it is unsolicited mail (spam), click on the following link to reclassify it: http://127.0.0.1:6083/Panda?ID=pav_232307&SPAM=true >-------------------------------------- > > > > - 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 [email protected] 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 [email protected] Mike Cantwell [email protected] For policy questions, send mail to: Jim Bacher: [email protected] David Heald: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
