January 13, 2012

3phase Power Misconceptions: Circuit Watts

Recently, we have been recommending more 3phase power solutions for people.  Frequently, the mere mention of a 3phase UPS creates fear and confusion.  Part of the problem is that 3phase UPS units were expensive to buy and even more expensive to maintain.  We still have business affiliates that make most of their money on service contacts on these older beasts.

Today's 3phase is cheaper, expandable, and near maintenance free.  But before you make the jump to the Symmetra PX 40... lets consider one aspect of 3phase.... CIRCUIT WATTS

  • 3phase is a method delivering power... what it ultimately delivers is still watts.  There is no difference between a 3phase phase watt and single phase watt.
  • Since watts are a result of volts x amps.... if you need more watts you must increase voltage and or amps.
  • And since your amperage is fixed at your panel or building, upping voltage is the best way to get more watts.
  • But if you are already running at high voltage and amperage is maxed... your only option is to goto 3phase.
Consider a 30amp circuit to a rack.  Notice how upping the voltage and phase delivers more watts or power.
  • At 120volt... your 30amp circuit provides 2.88kw
  • At 208volt... the 30amp circuit provides 4.99kw
  • At 3phase 208v... that same circuit provides 8.64kw
Just this one aspect gives you a glimpse of why 3phase power is seen by IT providers as the more effective way of delivering the wattage you need to your IT system.