T1=30;
T2=600;
c=383;
hustota=8500;
delkaIngot=3;
prumerIngot=0.1;
cas=15*60;
Vykon=(hustota/cas)π*delkaIngot*((((prumerIngot/2)))^2)*c*(T2-T1);
U1=230;
ω=314;
σ1=57000000;
μr1=1;
μ0=4.*π*(10^(-7));
σ2=40000000;
μr2=1;

a1=(Sqrt[(2/(ω*σ1*μr1*μ0))]);
a2=(Sqrt[(2/(ω*σ2*μr2*μ0))]);
delkaCivka=3;
prumerCivka=0.1+0.05;
d1=prumerCivka+a1;
d2=prumerIngot-a2;
alfa1=alfa2=1;
F=1;
R2=((π*d2)/(σ2*a2*delkaIngot));
R1=(n^2)*((π*d1)/(σ1*a1*delkaCivka))*1.2;
L1=μr1*μ0*((π*(d1^2))/4)*((n^2)/delkaCivka)*alfa1;
L2=μr2*μ0*((π*(d2^2))/4)*(1/delkaIngot)*alfa2;
M=μ0*((π*(d2^2))/delkaIngot)*n*F;

proud2=(Sqrt[(Vykon/R2)]);

rce1=U1-I1*R1-I*ω*L1*I1-I*ω*M*I2==0;
rce2=I2*R2+I*ω*L2*I2+I*ω*M*I1==0;

rce3=Abs[I2]==(Sqrt[(Vykon/R2)]);

FindRoot[{rce1,rce2,rce3},{{I1,100-100I},{I2,100-100I},{n,10.}}]

{rce1,rce2,rce3}//Simplify

Simplify[rce3/.Solve[{rce1,rce2},{I1,I2}][[1]]]//Chop

FindRoot[Simplify[rce3/.Solve[{rce1,rce2},{I1,I2}][[1]]]//Chop,{n,10}]

delkaCivka/(180*1.2)

Solve[{rce1,rce2},{I1,I2}]/.n->180

Abs[I1]/.Solve[{rce1,rce2},{I1,I2}]/.n->180

(Abs[I1^2]/.Solve[{rce1,rce2},{I1,I2}]/.n->180)*(R1/.n->180)