George - The answer to your question is: yes. However, in the US, this is type of system is used to deliver power to homes and there are either no or very few homes supplied with three-phase power. Such a system would be abhorrent to any user of all three phases, who would prefer the corner-grounding method.
Perhaps this thread has become a bit muddled in that I was responding to a question Doug McKean posed about grounding of delta secondaries. There are two basic methods, as I described. I was not trying to address the GFCI question or otherwise say that the center-grounded-delta configuration was suitable for other than power delivery to homes, receiving 120V line-to-neutral and 240V line-to-line. My apologies for the confusion. Regards, Peter L. Tarver Nortel ptar...@nt.com >---------- >From: Georg M. Dancau[SMTP:dan...@compuserve.com] >Sent: Thursday, February 26, 1998 3:47 AM > > Peter Tarver wrote: > > Delta-delta transformers are popular with the utilities for economy's > sake (they are less expensive than WYE transformers) For similar > reasons, some industrial applications distribute and use power within > their plants on delta feeds. > > In office environments, however, it's typical to use a WYE connected > secondary, i.e., 120Y/208V, for general appliance use and other WYE > connected configurations for lighting and other power. > > When a delta transformer is grounded, it typically occurs at either a > "corner", where two secondaries are electrically connected, or > "center-grounded" at the center of one of the secondaries. It is my > understanding that the latter case is typical for power provided to > homes in the US and is also referred to as "split-phase." > > Regards, > > Peter L. Tarver > Nortel > ptar...@nt.com > > >Hi Pete > >I want to address the issue of or <"center-grounded" at the center of >one of the secondaries>. > >Do you mean like this ? > > [Image] > >I never encountered this yet. In this case, the voltages of the three >active conductors with respect to earth would be: > >V(L1)=480V*sqrt(3)/2=415V >V(L2)=480V/2=240V >V(L3)=480V/2=240V > >The voltage of the imaginary center point would be about 208V. You would >have enormous leakage >currents through the Y capacitors in the power line filters. > >On the other hand, as far as I remember, the IEC 38 states, that for a >TN network, one active >conductor is earthed (not stating which one). In this case I do not see >any conformance with the IEC38. > >I'll be glad for any comment from the pstc community on this issue. > >Best regards > > >George > >-- >************************************************************** >* Dr. Georg M. Dancau * HAUNI MASCHINENBAU AG * >* g.m.dan...@ieee.org * Manager EMC Lab * >* TEL: +49 40 7250 2102 * Kampchaussee 8..32 * >* FAX: +49 40 7250 3801 * 21027 Hamburg, Germany * >************************************************************** >* home: Tel: +49 4122 99451 * Hauptstr. 60a * >* Fax: +49 4122 99454 * 25492 Heist, Germany * >************************************************************** > > > > >
