nce of copper;
? 0 = 4.3? 10-3 K-1 - is the temperature coefficient of copper; = 105 В° C - is permissible heat temperature of the winding.length of one turn
В
,
where h - is the distance between the core and the yoke, m; - is the diameter of the core, m.
but keeping some place in reserve, let
В
, (Iw) final - is the magnetic motive force of the electromagnet A;
? q - is the resistance of copper,?? m; в.ср. - Is average length of one turn, m; - is voltage, V.one must choose the most suitable diameter of the wire;
В
Then the cross-section of the wire is to be found:
В
,
where dw - is the diameter of the wire, mI find the number of turns in the coil
В
,
where U - is voltage, V; доп - is current density, A/m2;
? q - is the resistance of copper, ?? m; в.ср. - Is average length of one turn, m.the square of the winding is to be found;
В
, w - is the number of turns in the coil;
q0 - is the cross-section of the wire; з - is the space factor coefficient equaled to 0.656.the width of the winding can be found:
В
,
where Q0 - is the square of the winding, mm2; - is the length of the yoke, mm.
equivalent circuit magnetic steel
2.3. Determination of pure resistance and MMF of the wire
first, I find the resistance of the coil:
В
,
where? q - is the resistance of copper, ?? m;
w - is the number of turns in the coil;
lв.ср. - Is average length of one turn, m. p align="justify"> q0 - is the cross-section of the wire, m2.it is possible to calculate the current flowing in the winding:
В
, U - is the voltage in the winding, V; - is the resistance of the coil.it is necessary to check whether the current density was chosen correctly:
В
В
where I - is the current flowing in the winding, A; - is the cross-section of the wire, m2., the density is correct., it is possible to calculate the pure MMF of the coil:
В
The error is:
В
В
3. Determination of the magnetic flux
3.1. Calculation of air-gaps
task is to find the magnetic flux and electromagnetic force through the operating air gap of the electromagnet, figure 1.1., knowing next parameters: a = 10 mm; d = 25 mm; d2 = 20 mm; l = 250 mm; h = 80 mm;? =? 1 = 0.2 mm;
