sentences:  A voltage-fed inverter with a series connection to a parallel load is also known as a third order system.Basically this is similar to solid state, but in this system the series connected internal capacitor and inductor are connected to a parallel output tank circuit.The principal advantage of this type of system is the robustness of the inverter due to the internal circuit effectively isolating the output circuit making the switching components less susceptible to damage due to coil flash-overs or mismatching.