Construction of DC Machines %2B(1).png)
Important Parts of a DC machines:
(1) Yoke
(2) Field winding
(3) poles
(4) Armature
(5) commutator
(6) Bearings.
( 1) Yoke:
- Yoke is Also called as frame. It provides protection to the rotating and other parts of the machine from moisture, dust etc.
- Yoke is an iron body which provides the path for the flux. This is essential to complete the magnetic circuit.
- It provides the mechanical support for the poles.
- Material used for yoke are basically the low reluctance materials such as cast iron, silicon steel, rolled steel, cast steel etc.
( 2) Field winding
-The coils wound around the poles cores are called field coils.
- The field coils are connected in series to form the field winding
-Current is passed through the field winding in a specific direction, to magnetize the poles and pole shoes. The magnetic Flux is thus produced in the air gap between the poles shoes and armature.
-The field winding is also called as exciting winding.
-The material used for the field conductor is copper.
- Due to the current flowing through the field winding alternate N and S poles are produced.
which pole is produced at a particular core is decided by the right hand thumb rule for a current carrying circular conductor.
( 3) Poles
- A pole of a generator is an electromagnet. The field winding is wound over the poles.
- Poles produced the magnetic flux when the field winding is excited.
- Pole shoe is an extended part of a pole. Due to its typical shape, it enlarge the area of the pole.
- Due to this enlarge area, more flux can pass through the air gap to armature.
- A low reluctance magnetic material such as cast steel or cast iron is used for the construction of a pole or pole shoe.
- The construction of poles is done using the lamination's of particular shape. This is to reduce the power loss due to eddy currents.
(4) Armature
- Armature core is a cylindrical drum mounted on the shaft.
- It is provided with a large number of slots all over its periphery.
- All these slots are parallel in these slots.
- Armature core provided a low reluctance path to the flux produced by the field winding.
- High permeability,low reluctance materials which helps in cooling the armature core.
- The laminated construction is used to produce the armature core to minimize the eddy current losses.
(5) commutator
- A commutator is s cylindrical drum mounted on the shaft along with the armature core.
- It is made of a large number of wedge-shaped segment of hard-drawn copper.
- The segments are insulated from each other by thin layers of mica.
- The armature winding is tapped at various points and these taping s are successively connected to various segments of the commutator
functions of a commutator:
- It convert the alternating current to Direct current
- It collects the current from the armature conductors and passes it to the external load via-brushes.
- For dc motors, it helps to produce a unidirectional torque.
Material used:
- The commutator segments are made of copper and the insulating material between the segments is mica.
Important Parts of a DC machines:(1) Yoke
(2) Field winding
(3) poles
(4) Armature
(5) commutator
(6) Bearings.
( 1) Yoke:
- Yoke is Also called as frame. It provides protection to the rotating and other parts of the machine from moisture, dust etc.
- Yoke is an iron body which provides the path for the flux. This is essential to complete the magnetic circuit.
- It provides the mechanical support for the poles.
- Material used for yoke are basically the low reluctance materials such as cast iron, silicon steel, rolled steel, cast steel etc.
( 2) Field winding
-The coils wound around the poles cores are called field coils.
- The field coils are connected in series to form the field winding
-Current is passed through the field winding in a specific direction, to magnetize the poles and pole shoes. The magnetic Flux is thus produced in the air gap between the poles shoes and armature.
-The field winding is also called as exciting winding.
-The material used for the field conductor is copper.
- Due to the current flowing through the field winding alternate N and S poles are produced.
which pole is produced at a particular core is decided by the right hand thumb rule for a current carrying circular conductor.
( 3) Poles
- A pole of a generator is an electromagnet. The field winding is wound over the poles.
- Poles produced the magnetic flux when the field winding is excited.
- Pole shoe is an extended part of a pole. Due to its typical shape, it enlarge the area of the pole.
- Due to this enlarge area, more flux can pass through the air gap to armature.
- A low reluctance magnetic material such as cast steel or cast iron is used for the construction of a pole or pole shoe.
- The construction of poles is done using the lamination's of particular shape. This is to reduce the power loss due to eddy currents.
(4) Armature
- Armature core is a cylindrical drum mounted on the shaft.
- It is provided with a large number of slots all over its periphery.
- All these slots are parallel in these slots.
- Armature core provided a low reluctance path to the flux produced by the field winding.
- High permeability,low reluctance materials which helps in cooling the armature core.
- The laminated construction is used to produce the armature core to minimize the eddy current losses.
(5) commutator
- A commutator is s cylindrical drum mounted on the shaft along with the armature core.
- It is made of a large number of wedge-shaped segment of hard-drawn copper.
- The segments are insulated from each other by thin layers of mica.
- The armature winding is tapped at various points and these taping s are successively connected to various segments of the commutator
functions of a commutator:
- It convert the alternating current to Direct current
- It collects the current from the armature conductors and passes it to the external load via-brushes.
- For dc motors, it helps to produce a unidirectional torque.
Material used:
- The commutator segments are made of copper and the insulating material between the segments is mica.
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