> From: [email protected] [mailto:[email protected]] > On Behalf Of Luke S. Crawford > > My understanding is that my equipment runs more efficently on 208v > than on 120v.
Not necessarily. The problem is as simple as this: Your equipment expects steady DC voltage, and the power company provides AC. When you go through your A2D conversion, you have storage elements in your power supply which continue to power the DC equipment while the AC voltage is on the downswing or the backswing. If the engineers aren't careful in the design of your DC power supply, the stored energy may go to waste. This is the difference between VA and W. VA is always >= W, and the difference between VA and W is wasted in heat. Ideally, you want your power factor (pf) to be precisely 1.0. This means VA=W, and perfect efficiency in the A2D conversion. Perfection is not realistic, but something over 95% efficiency is very realistic. So there are a few ways of dealing with this. You can use 2-phase or 3-phase power (240V or 208V) to create a smoother AC power signal, thus utilizing less storage elements, and producing less waste. That is true. Or you can just design a smarter A2D power supply, which efficiently uses the 120V single phase power. Since 208V 3-phase power is rare, it's expensive. Most (but not all) equipment manufacturers have decided to address the problem by selling smarter power supplies. For example, I have a small farm of generic black boxes, and when I measure the VA and W of these systems, I see something like 60% efficiency. Loads of waste. But when I hook up my kill-a-watt to a Dell server or workstation... Just the "typical" ones, without the Dell Upgraded "Green" or "Eco friendly" power supplies... I get no less than 95% efficiency. I can only imagine the "green" power supplies must be something like 99% efficient. So. In the end, Luke: Your curiosity about 120V single-phase, versus 240V or 208V, 2 or 3 phase... Depends on your equipment. If you can, you should measure the VA and W consumption of your equipment, and let that be your guide, Re: whether or not you care about more phased power. _______________________________________________ Tech mailing list [email protected] https://lists.lopsa.org/cgi-bin/mailman/listinfo/tech This list provided by the League of Professional System Administrators http://lopsa.org/
