The series electromagnet is energized by a coil known as current coil which is connected in series with the load so that it carry the load current. The flux produced by this magnet is proportional to and in phase with the load current.
In DC microgrid system, Efficiency α 1/Pin For 1 kW loss injecting power is 20 kW For 1.5 kW loss injecting power will be proportional to 30 kW So, Efficiency will be reduced 0.025