AC Watts vs DC Watts
Are the rated inverter AC watts just V*A or are they an RMS average? And would the DC wattage required to drive the inverter's AC watts equal the AC Watts? (less efficiency losses) Elsewhere I'm...
Forum Discussion
scrubjaysnest wrote:
The technical answer is AC watts are V*A*cos(theta) where theta is the angle that results from any phase shift caused by the inverter or it's load(s) DC watts on the other hand are pure restrictive, no phase shift.
Probably just using the rule of thumb, DC amps = 10*AC amps is close enough to determine the watts either way.
most inverters are pretty efficient, in the high 90% range. so 10X AC current will get you in the ballpark.
exactly. and for a pure resistive load AC watts = Vrms*Irms
and yes, for reactive loads V and I are vectors (magnitude and angle) rather than a scalar (magnitude only) so one needs to apply vector math. Or if one knows the Power Factor, watts=VA* power factor.
And in reality virtually all inverters are rated for VA, not watts if your driving a reactive load such as a microwave oven.
