Sinusoidal voltage is applied to the electric coil with ferromagnetic core.

**Problem Type:**

An axisymmetric problem of nonlinear transient magnetics.

**Geometry:**

Due to the model symmetry only the right half of the coil is presented in the model (shown by upper half of its cross-section). Therefore the circuit elements' values are defined twice less than in the real object.

**Given:**

Magnetic permeability of the steel core *μ* - *nonlinear*;

Conductivity of the steel core *g* = 10,000,000 S/m;

Magnetic permeability of the winding *μ* = 1;

Conductivity of the winding (copper) *g* = 56,000,000 S/m;

Number of turns *w* = 120;

Applied voltage value (amplitude) *U* = 10*sqrt(2) V;

Frequency *f* = 50 Hz.

**Problem:**

Determine the electric current within the coil windings.

**Solution:**

The sinusoidal current wave period is T = 1 / f = 0.02 sec. We choose the time step of 0.0005 second that guarantees a smooth plot. The finishing time 0.2 sec includes 10 periods and is long enough to fade out initial transient currents. To reduce the results file size only the last period is stored (starting from moment 0.18 sec).

**Results:**

The current in the winding is: *I(t)* = 59.6·cos(*t*·2π/T - 166°)

See the *TECircuit1.pbm* problem in the Examples folder.