INDUCTORS IN PARALLEL

If there is no mutual inductance among two or more parallel-connected inductors, their values add up like the values of resistors in parallel.
Suppose that you have inductances L₁, L₂, L₃,…, Ln connected in parallel (Fig. 1). Then you can find the reciprocal of the total inductance 1/L using the following formula:

Fig. 1. Inductances in parallel add like resistances in parallel.

1/L = 1/L₁+1/L₂ +1/L₃ + ...  +1/L_n
The total inductance L is found by taking the reciprocal of the number you get for 1/L. That is:
L = 1/ (1/L₁+1/L₂+1/L₃+...+1/L_n) = (1/L₁+1/L₂ +1/L₃ + ... +1/L_n)^-1
Again, as with inductances in series, it is important to remember that all the units have to agree. Don’t mix microhenrys with millihenrys or henrys with nanohenrys. The units you use for the individual component values will be the units you get for the final answer.
Let’s not concern ourselves with what happens when there is mutual inductance. Sometimes mutual inductance increases the net inductance of a combination to values greater than the formulas indicate, and in other cases mutual inductance reduces the net inductance of a combination. Engineers sometimes must worry about mutual inductance when building radios or other sophisticated electronic circuits, especially at high frequencies.