With heavy inductive loads, the product V*1 (VA on the AC side) is much larger than the actual watts delivered. E.g. Inductive motors, fluorescent lamps, etc. This means some of the energy is stored in the inductivity of the load and then flows back to the battery. These inductive currents cause heat dissipation in the power semiconductors and in the cables as well. As the capacity is used up for reactive currents, there is “no room” for active currents.
WHY DOES MY 600VA INVERTER NOT WORK ON A LOAD DECLARED 600W?
- With inductive loads the VA value is bigger than the Watts value. E.g. 600W load, cos phi 0.6 results in 1000VA!
- With motors often the mechanical output is declared so the VA rating is even higher.
- Another cause for malfunction is inrush currents (5 to 10 times nominal current with motors).