Following are three types of dc machines:
1) DC generator:
“Energy can be converted from one form to other form”
It is rotated by prime mover and produces a dc voltage. i.e. Convert mechanical energy into electrical energy.
2) DC Motor :
It receives energy from a dc voltage source and rotates at Speed proportional to the applied voltage i.e .converts electrical energy into a mechanical energy.
3) Windings :
In DC machine there are two windings :
- Field Winding : It is Stationary Which does not move.
- Armature Winding :It placed in rotor and it is movable (Simple Loop Generator).
Draw wave of DC generator in following Case.
Emf Induced in side Armature
- A single turn copper Coil is made from two Conductors A & B
- Its turn coil is rotating about its own axis in a magnetic field provided by permanent magnet with two poles N and S .
- The ends of coil are joined in two silpring C1 and C2.
- The slip ring rotate along with shaft the brushes do not rotate induce .
- Brushes Collect the current in the coil and convert into external lead resistances ’R’
- as coil rotates flux limned with it changes Hence an emf is induced magnetic Induction .
- The induced emf is zero when plane of Contactor motion is parallel top lane of magnetic flux.
- this induced emf maximum when the perpendicular to the plane of magnetic flux.
- the induced emf in single turn coil is given by,
e=blvsin?. Here, B, l and u are magnetic flax density, length of conductor and velocity of moving conductor which are constant.
.’. e =k sin?.
Hence e is directly proportional to sin? .’. shape of induced emf is sine wave.
- It was single than alternator produce sine wave.