## 09/09/2017

### Principle of DC Generator

Principle of DC Generator

• It is an electrical machine which converts mechanical energy into electrical energy.
• The principle of operation of the dc generator is based on dynamically induced emf.
• Whenever a rotating conductor cuts magnetic flux, dynamically induced emf is produced in it according to the Faraday's law of electromagnetic induction.

The magnitude of induced emf is given by

e = BLVsin θ

Where

B = Flux density ( Weber / meter2 or Tesla )

L = Length of conductor ( meter )

V = Velocity of conductor movement ( meter /second )

θ = Angle between flux line and direction of conductor movement. Obviously

•  Therefore the induced emf e = 0 for θ = 0° and  e = Maximum for θ = 90°
• It means that when the conductor motion is parallel to the line of magnetic flux, the induced emf is zero whereas when the conductor motion is perpendicular to the line of magnetic flux, induced emf is maximum.
• The direction of the induced emf is found out by Fleming’s right hand rule.

Fleming's Right hand rule

• It states that "Hold the right hand such that the thumb, first finger and middle finger are mutually perpendicular.
• If the thumb indicates - direction of motion of conductor and first finger indicates - direction of magnetic field, the middle finger shows the direction of induced emf.

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