Electrical DC Machine Basic Formula Principle of Operation

Electrical DC Machine Basic Formula Principle of Operation

Some Basic Formula:

Right‐hand screw rule (cross product operation in vector algebra)

A1 X A2= A3

A1, A2, and A3 are vectors. Rotate RH fingers from the direction of the first vector , A1, to the

direction of the second vector, A2, through the small angle (<180o) between them; the direction

of A3 is then given by the extended RH thumb. In our applications, the magnetic field B is always

the second vector.

Given a straight conductor lying in a magnetic field, and oriented perpendicular to the direction

of the field. Let

B= magnetic flux density (also called magnetic induction), [T=tesla=weber/m2];

L=active length of conductor,[m]. u

Induced voltage (emf): 

E=B.L.u.sinα volts

u= speed of conductor perpendicular to its length[m/s];

α= small angle from u to B.

Direction of E : RH screw rule from u to B .

Developed force:

Fd= B.I.L newtons [N]

I= current through conductor, [A].

Direction of Fd : RH screw rule from I to B.