About electric motor & generator....
Asked by syscon | 6th Feb, 2010, 01:26: PM
The primary difference between a DC motor and an AC motor is finding a way to change the direction of current flow. In direct current, electric current always moves in the same direction. That means that the wire loop in the motor will stop turning after the first half revolution. Because the current is always flowing in the same direction, the resulting magnetic field always points in the same direction.
To solve this problem, the wire coming from the DC power source is attached to a metal ring cut in half, as shown in the figure. The ring is called a split-ring commutator. At the first moment the motor is turned on, current flows out of the battery, through the wire, and into one side of the commutator. The current then flows into the wire loop, producing a magnetic field.
Once the loop begins to rotate, however, it carries the commutator with it. After a half turn, the ring reaches the empty space in the two halves and then moves on to the second half of the commutator. At that point, then, current begins to flow into the opposite side of the loop, producing the same effect achieved with AC current. current flows backward through the loop, the magnetic field is reversed, and the loop continues to rotate.
Electrical generators rotate a coil of wires through a magnetic field. The difference between an AC and a DC generator is that the AC generator uses slip rings to transfer the current to the electrical circuit, while the DC generator uses a split-ring commutator.
Hope this helps.
Answered by | 8th Feb, 2010, 11:18: AM
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