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3. (b) i) DC Motor - Coggle Diagram
3. (b) i) DC Motor
Applications
Shunt DC Motors
Owing to the fairly constant speed and medium starting torque of shunt DC motors, they are used in the following applications:
- Centrifugal and reciprocating pumps
- Lathe machines
- Blowers and fans
- Drilling machines
- Milling machines
- Machine tools
Series DC Motors
Owing to the high starting torque and variable speed of series DC motors, they are used in the following applications:
- Conveyors
- Hoists, Elevators
- Cranes
- Electric Locomotives
Cumulative Compound DC Motors
Owing to high starting torque of cumulative compound DC motors, they are used in the following applications:
- Shears
- Heavy Planers
- Rolling mills
- Elevators
Operations
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The basic working principle of the DC motor is that whenever a current carrying conductor places in the magnetic field, it experiences a mechanical force
DC motors operate on Faraday's principle of electromagnetism which states that a current-carrying conductor experiences a force when placed in a magnetic field
According to Fleming's "Left-hand rule for electric motors," the motion of this conductor is always in a direction perpendicular to the current and the magnetic field
Mathematically, we can express this force as F = BIL (where F is force, B is the magnetic field I stand for current, L is the length of the conductor)
Common Failures
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There are many reasons for its incapability to start such as low voltage supply, wrong connection, excessive load, frozen bearing ground fault and so forth
Sparks in the brushes is another problem associated with the dc motors. Sparks may be caused due to insufficient contact and inappropriate size of the brushes
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