I don't see any real advantage in isolation for this application. VFDs are designed to be run directly from the mains. If your mains supply has an RCD it is actually an advantage if you aren't isolated. That way any earth leakage will knock out the trip.
Les On 22/10/2013 11:06, Erik Christiansen wrote: > > Wiring the secondary of any step-down transformer in series with the > primary, phased either for step-up or step-down, forms an > autotransformer: > > http://en.wikipedia.org/wiki/Autotransformer > > Now we have no isolation from the supply side. > > When I did that to use a European 220v router on Aussie 240v mains, I > just grabbed a suitable transformer from the junk box. Its secondary > current rating exceeded the router's consumption, and had a secondary > voltage of 24v, giving a choice of 216v or 264v. > > More recently, about twenty turns of insulated wire added to a toroidal > power transformer tweaked the secondary voltage to provide what I > needed, while leaving it as a step-down transformer with full isolation. > > Erik > ------------------------------------------------------------------------------ October Webinars: Code for Performance Free Intel webinars can help you accelerate application performance. Explore tips for MPI, OpenMP, advanced profiling, and more. Get the most from the latest Intel processors and coprocessors. See abstracts and register > http://pubads.g.doubleclick.net/gampad/clk?id=60135991&iu=/4140/ostg.clktrk _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
