ω=314.;
T=((2Pi)/ω);
Uz=230*(Sqrt[2])*Sin[ω*t+0.4];
R=15;
L=0.2;
eqns={u1[t]==Uz,u1[t]-u2[t]==R*i[t],u2[t]==L*i'[t],i[0]==0};
tmax=5T;
sol=NDSolve[eqns,{u1,u2,i},{t,0,tmax},StartingStepSize->(10^(-11))][[1]];
Plot[i[t]/.sol,{t,0,tmax},AxesLabel->{"t [s]","i [A]"},PlotStyle->Thick]