Why is power draw measured in WATTS ( which is volts multiplied by amperage ) but power production or power sources are measured in VA ( volt amps ). Are they not identical? What’s the reason for the difference.
In: Engineering
For a purely resistive load, like a light bulb or heater, volts times amps equals watts. But many loads are not purely resistive; they can also be capacitive or inductive. By far the most common of the two is inductive: most motors, for example, are inductive loads. These loads consume power but “return” some of it without using it. So there’s a thing called a “power triangle” that shows the relationship between the “real” power (measured in watts; this is the actual amount of power consumed), the “reactive” power (measure in volt amps reactive; this is the power that gets “returned”), and the “apparent” power (measured in volt amps: for a purely resistive load, this will match the real power).
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