Wow, Scott35, lots of detail.
I wanted to understand what people thought of a single phase 208 volt system. In the form of transformers, it is easier to discuss and understand, so that's why I asked in terms of transformers first. But really, I'm looking at this in terms of UPSes/inverters, and how a 208 volt system is formed. I have a choice between two kinds of UPSes for a bunch of computers:
1. Has one output inverter producing 208V directly (can be programmed to one of 200/208/220/230/240 volts, 50 or 60 Hz). Appears to NOT be grounded in any way. Questions to their tech support people get strange answers, but finally conclude it is ungrounded (neither terminal is a grounded conductor). Any relation to ground will be through the inverter circuitry itself. The input is 3 wire and has an L6-30P.
2. Has two output inverters producing 120V directly (can be programmed to one of 100/110/115/120/127 volts, 50 or 60 Hz). Specs also indicate they can be programmed to 120, 180, and 240 degree phase angles (I guess the 240 is there to reverse any sense of phase rotation without having to reverse the conductors). So apparently it can produce any of 173/190/200/208/220/230/240/254 volts L-L output through appropriate combinations of L-G/N voltage and phase angle. The input is 4 wire (A/B/N/G) and has no plug (why not an L14-30P).
I'm leaning toward the latter because it is grounded. The former is lower in cost and was already ordered before I was hired. Normally, when trying to evaluate equipment, vendors bring along a sample unit and often leave it for a few days trial. This isn't practical in this case.
I guess I biased my question when I replied with asking how to ground the transformer secondary. I wondered if someone might suggest to just leave it ungrounded. Would you do that for a bunch of computers with multiple ungrounded UPSes?
