Power supplies, PoE, input power
Posted on 2012-08-14
The question regards power input, and the affect on this on PoE capability. The following is from an HP datasheet regarding 1500W power supplies for several of their chassis switches:
"Standard PoE+ power supply for zl series switches. Supplies 300W for PoE+ power at 110-127 volts, 900W for PoE+ power at 200-240 volts, and 600 W for switch power. "
These are 1500W switches. According to this, they can/will supply chassis power at 600W, but the PoE budget will triple based on the input power (110 vs. 2x0).
Please explain why(if) this is true. I've always thought it was a simple formula, where voltage (x) input power (=) watts. If a power supply is rated at 1500W, then why would input power affect the amount of power the supplies could provide for PoE device support?
Thank you - as always, reference links/docs are appreciated.