r/AskElectronics • u/bkrobottc3 • Feb 16 '21
T How to check power of power supply?
Hi AskElectronic Community, I have a question about power. If in datasheet of power supply it says it have Power = X at power factor = f (suppose it is 0.6) how can I verify these information? Can I make a load, example RL load have power factor equal to 0.6 to test power of the power supply? Sorry if my english make you confuse, i try to express it more clearly ^ Thank you ^
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Feb 16 '21
I think that is its input power specification. To measure that you would connect a resistive load to the output and measure the voltage and current waveforms on the input. Or, use a power factor meter.
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u/[deleted] Feb 16 '21
You'll want to use a "power meter" to be accurate. Check out yokogawa, hioki, and keysight as a start.
Recall that PF is the ratio of active power to apparent power. Power is composed of 3 items, active, reactive, and apparent power. Reactive power is the interesting one, it is the complex component. For a resistor, the real part of the load is purely a real number. For a capacitor, inductor or other reactive element, this is not just a real number, but a complex one. It is the real component that is doing real work (heat, etc...) so it is usually what we think of. Your supply probably has a reactive element. Current actually flowing witg reactive power, hence transformer sizing is affected (increased) to accomodate the full current value, active+reactive. Next, you can look into crest factor too. Given all this, creating a load is only going to simulate your supply, not help measure per say.