Electrical Engineering ⇒ Topic : Series Aiding

Consider two coils connected in series as shown in Figure.

Let L₁ = inductance of first coil

      L₂ = inductance of second coil

      M = mutual inductance between the two coils

Series-aiding:-This is the case when the coils are so arranged that their fluxes *aid each other i.e. in the same direction as shown in Figure (a). Suppose the current is changing at the rate di/dt. The total induced e.m.f. in the circuit will be equal to the sum of e.m.f.s induced in L₁ and L₂ plus the mutually induced e.m.f.s, i.e

                                                        FIGURE (A)

                           ... in magnitude

  = (L₁+ L₂ + 2M) di/dt

If L_T is the total inductance of the circuit, then,

L_T = L₁+ L₂ + 2M                                                               ...fluxes additive