Anything special about converting VAX 11/780 to single phase?

Andreas, The power distribution of a VAX 11/780 is much simpler than that. There is only one three-phase transformer in the entire machine, and it is used to power the shutdown interlocks. The three phases are not combined into any "wye" or "delta" arrangement using a transformer (other than the interlock). The front side of the power distribution panel consists of a bunch of standard 120V three-prong household outlets, and various portions of the VAX are connected to these outlets. It's very easy to convert an 11/780 to run from single-phase power, the problem is the high current draw, which is more than the typical 15A feed in our houses. I've been running mine for short periods of time, which each phase plugged into a different branch circuit in my house. This really makes GFI protected circuits go bonkers (for obvious reasons), but I've been very careful not to exceed ampacity of any of the branches. I wouldn't recommend this to everyone, though. I brought home a Fluke 41 Power Harmonics Analyzer and made a simple test harness so I can actually measure what is going on with my modification to the 11/780. When Gunther was visiting, we ran it for about twenty minutes, and that was the longest run of the machine in my house to date. I was also very cautious to make sure that none of the "phases" were causing any excessive heating in the wires, however, this is not a good safety test of the modification. After safety checks using the 41, my next step is to install those small inline "Power Planners" to the cooling fans. That should cut the power requirements of the 780 by a few hundred watts. I've tested those Power Planners, and for typical AC motors that do not run under a heavy load, they really do work and cut electrical consumption. They do generate harmonics, but not any worse than your typical PC switching power supply. My eventual goal is to run the 780 from a 240V source. Any yes, my wife thinks it nuts. - Matt At 01:11 PM 2/1/2002 +0100, you wrote: Matthew Sell Programmer On Time Support, Inc. www.ontimesupport.com (281) 296-6066 Join the Metrology Software discussion group METLIST! http://www.ontimesupport.com/cgi-bin/mojo/mojo.cgi "One World, One Web, One Program" - Microsoft Promotional Ad "Ein Volk, Ein Reich, Ein Fuhrer" - Adolf Hitler Many thanks for this tagline to a fellow RGVAC'er...