• subhankar ghosh

MemberJan 11, 2013

## Starting the generator : What if conductor is rotated anticlockwise?

What happen if we rotate the conductor anticlockwise instead of clockwise for starting the generators?

Generators convert mechanical energy into electrical energy via electromagnetic induction.

The direction in which a generator's rotor (or armature) spins affects the phase sequence or the polarity of the generated voltage.

1. Faraday’s Law of Electromagnetic Induction: The most fundamental principle that governs this phenomenon is Faraday's Law. It states that the magnitude of the induced EMF in any closed circuit is directly proportional to the rate of change of the magnetic flux through the circuit. In simpler terms, when you rotate the armature inside the magnetic field, an EMF is induced.

2. Direction of Induced EMF (Fleming's Right-Hand Rule): According to Fleming's right-hand rule, if you stretch out your thumb, index finger, and middle finger of your right hand such that they are mutually perpendicular, with:

• Thumb pointing in the direction of motion of the conductor

• Index finger pointing in the direction of the external magnetic field

• Middle finger will point in the direction of the induced current.

This rule can give you an intuitive understanding of the direction of current flow based on the direction of rotation and the magnetic field.

3. Implications of Anticlockwise Rotation:

• Single Phase Generator: For a single-phase generator, rotating the armature in the opposite direction will simply reverse the polarity of the output voltage. That means, if you originally got a positive voltage peak when rotating clockwise, rotating anticlockwise will give you a negative voltage peak first.

• Three Phase Generator: For a three-phase generator, the anticlockwise rotation will change the phase sequence. If the original sequence was ABC (when rotating clockwise), the new sequence will be ACB (when rotating anticlockwise).

4. Practical Implications: In real-world applications, especially where synchronization is required (e.g., in power grids), the direction of rotation is crucial. If a generator is rotated in the opposite direction, it could lead to out-of-phase conditions, which can be harmful and can damage equipment.

5. Starters & Modern Generators: It's worth noting that most modern generators and motors have starters or controllers that ensure the correct rotation direction. In some cases, if the rotation is not as expected, the equipment may not start at all, or protective circuits may intervene.

In conclusion, the direction of rotation in a generator is essential to determine the phase sequence and the polarity of the generated voltage. While reversing the rotation might seem like a simple change, it has implications that are crucial in synchronized systems and power networks. Always ensure that equipment is rotating as intended to prevent possible damages or out-of-phase conditions.

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Replies
• MemberJan 11, 2013

According to Fleming's rule in the opposite direction Emf will be induced.
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• MemberJan 21, 2013

the polarities are reversed...and the current is generated in the opposite direction
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• MemberJan 30, 2013

#-Link-Snipped-# sir pls make some light on this question
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