I have a 48 V 65 W power supply plugged into my Kill A Watt meter.
I'm not so sure it is as efficient as the label suggests.
These are the calculations I have made:
$$S = V \cdot I$$ in VA the apparent power. $$232.6~V \cdot 0.25~A = 58.15~ VA$$
$$pf = P/S ~ [W]/[VA]$$
$$P = V\cdot I\cdot pf ~[W]$$
$$27.4~W/58.15~VA = 0.41~ [pf]$$
Does this sound like the efficiency of a power supply marked VI?
Whilst I realise pf is not efficiency, my understanding is that to be more efficient the pf has to be high (close to 1) and this looks like I have less than half?
I have seen that efficiency, of a class VI power supply, should be a minimum efficiency of 86 % and this doesn't look like its near this?
Am I wrong?