Inductors In Series:

As long as the magnetic fields about inductors do not interact, then the inductances in series add such as resistances in series. The total value is the sum of the separate values. It is significant to be sure that you are using the similar size units for all the inductors whenever you add their values.

Assume that you have inductances L1, L2, L3,..., Ln associated in series as shown in figure below. As long as the magnetic fields of the inductors do not interact- that is, as long as there is no mutual inductance among or between the components-the total inductance L is given by the formula as follows:

L = L1 + L2 + L3 +...              + Ln

Figure: Inductances in series add like resistances in series.