What is armature reaction in dc machine?
What is armature reaction in dc machine?
3.10 Armature reaction in d.c. generators. Armature reaction is the effect on the main field flux of that flux set up by the currents in the armature winding. The effect is the same for both lap- and wave-wound machines.
How can the armature reaction be reduced in a dc machine?
1) The armature reaction causes the distortion in main field flux. This can be reduced if the reluctance of the path of the cross-magnetizing field is increased. The armature teeth and air gap at pole tips offer reluctance to armature flux. Thus by increasing length of air gap, the armature reaction effect is reduced.
What is armature reaction briefly explain?
Definition of armature reaction : a magnetomotive force set up by the current induced in the armature of a dynamo that results in altering as to both magnitude and direction the flux due to the field magnet.
What is armature reaction PDF?
Armature Reaction: The effect of magnetic field set up by armature current on the distribution of flux under main poles of a generator. The armature magnetic field has two effects: (i) It demagnetises or weakens the main flux and (ii) It cross-magnetises or distorts it.
What is armature reaction and types?
What is Armature Reaction? In a DC machine, two kinds of magnetic fluxes are present; ‘armature flux’ and ‘main field flux’. The effect of armature flux on the main field flux is called an armature-reaction. The EMF can be induced within the armature conductors whenever they slash the lines of the magnetic field.
What is DC motor applications?
DC machines are also used in applications where high starting torque and accurate speed control over a wide range are important. Major applications for DC motors are: elevators, steel mills, rolling mills, locomotives, and excavators. Like other rotating machines, DC motors result from the interaction of two magnets.
How does a DC motor work step by step?
In a DC motor, the stator provides a rotating magnetic field that drives the armature to rotate. A simple DC motor uses a stationary set of magnets in the stator, and a coil of wire with a current running through it to generate an electromagnetic field aligned with the centre of the coil.
How are armature reactions corrected?
The effect of armature reaction can be neutralized by use of compensating winding. It is always placed in series with armature winding. The armature ampere conductors under pole shoe must be equal to compensating winding ampere conductors which will compensate armature mmf perfectly.
What are the effects of the armature reaction in DC machine?
The adverse effects of armature reaction: Armature reaction weakens the main flux. In case of a dc generator, weakening of the main flux reduces the generated voltage. Armature reaction distorts the main flux, hence the position of M.N.A. gets shifted (M.N.A. is perpendicular to the flux lines of main field flux).
What is armature reaction in dc machine PDF?
What are the types of armature reaction?
Types of Armature-Reaction
- Demagnetization of the stator field.
- The cross magnetization of the stator field.
How many types of armature reactions are there?
two types
Types of Armature-Reaction Generally, these are classified into two types which include the following. The Demagnetization reduces otherwise weakens the main flux, whereas the cross magnetization distorts the main flux.
What are the 4 types of DC motor?
There are 4 major types of DC motor. They are: Series DC Motor. Shunt/Parallel DC Motor….Types of DC motor when listed sequentially:
- Permanent Magnet DC Motor.
- Shunt Motor.
- Series Motor.
- Compound Motor is again classified into.
- Short Shunt Motor.
- Long Shunt Motor.
- Differentially Compound.
- Cumulative Compound.
What is DC motor with diagram?
Difference Between Dynamo and DC Motor
| Sr No. | Dynamo | DC Motor |
|---|---|---|
| 2. | Here normally permanent magnet is used or electromagnets made up of windings | Made of miniature size of permanent magnet |
| 3. | It can operate through Self Excitation or Separate Excitation | It is usually excited by permanent magnet present. |
How is an armature reaction created in a DC generator?
The current flowing through the armature conductors creates a magnetic field, which is called as armature flux. This armature flux distorts and weakens the magnetic flux produced by the main poles. This effect of armature flux on the main flux is known as armature reaction.
What is the main effect of armature reaction?
Armature reaction has two undesirable effects: First, it distorts the main field. Secondly, it reduces the main field flux or both. When the main field is distorted, then there will be a cross magnetizing effect.
What is armature motor?
The armature is an integral part of the motor (or generator), as this is the component that carries the alternating current (AC) in an electric machine. The armature conducts AC, even on Direct Current (DC) machines using the commutator (which reverses current direction every so often) or due to electronic commutation.
What is the difference between an armature and a rotor?
In a generator and a motor, a rotor rotates and the stationary part of the motor is known as a stator. Similarly an armature carries current while field windings produce the magnetic field needed to excite the generator and the motor.
How does an armature reaction affect a DC generator?
Armature Reaction in DC Generator. It is the opposition of flux produced by the main winding and armature winding.
Why does an armature reaction occur in a DC motor?
This is expected because when current flows through the armature conductors of a DC motor, it produces flux (armature flux) which lets on the flux produced by the main poles. For a motor with the same polarity and direction of rotation as is for the generator, the direction of armature reaction field is reversed.
Why armature core is laminated in DC machine?
Why is the armature core of a DC machine laminated but the yoke is not? Armature core rotates and comes under N and S poles alternately and this flux variations produce hysteresis and eddy current losses in the core and hence the core is laminated. The yoke is stationary and no flux variations take place and hence there is no iron losses.
What is the effect of armature reaction?
The effects of Armature Reaction are as follows:- Because of the armature reaction the flux density of over one-half of the pole increases and over the other half decreases. The total flux produces by each pole is slightly less due to which the magnitude of the terminal voltage reduces.
