Explanation: Initially at unsaturated condition in a DC machine armature reaction lies along the q-axis. It will cause no change in flux/pole if iron is unsaturated. The demagnetizing component acts in the opposite direction, reducing flux/pole in a machine, which will ultimately reduce generator emf..
Herein, what is saturation in machines?
Saturation means that when input exceeds a particular limit, the output becomes constant ,i.e, it saturates.In a DC machine the induced EMF increases as the field current increase. But after a certain level of field current, the core saturates and the flux induced is constant even if the field current increases.
Similarly, when armature current is increased in a DC motor its armature reaction will? Armature reaction is effect of armature flux on main field flux. Basically there are two windings in a dc motor - Armature winding (on rotor) and field winding (on stator). When we excite the field winding, it produces a flux which links with the armature. This causes an emf and hence a current in the armature.
Keeping this in consideration, what is the effect of 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 saturation effect?
Saturation Effect. the decrease in the intensity of a spectral line (an absorption or emission line) with increasing power of the external resonant electromagnetic radiation.
Related Question Answers
What is H in BH curve?
B-H curve is used to show the relationship between magnetic flux density (B) and magnetic field strength (H) for a particular material. When tested experimentally, a ferromagnetic (i.e. strongly magnetic) material such as iron will produce a curve similar to that shown above.What are hysteresis losses?
Hysteresis loss is due to the reversal of magnetization of transformer core whenever it is subjected to alternating nature of magnetizing force . Whenever the core is subjected to an alternating magnetic field, the domain present in the material will change their orientation after every half cycle.How is eddy current produced?
Eddy currents are currents which circulate in conductors like swirling eddies in a stream. They are induced by changing magnetic fields and flow in closed loops, perpendicular to the plane of the magnetic field. Like any current flowing through a conductor, an eddy current will produce its own magnetic field.What is meant by hysteresis loop?
hysteresis loop in British English noun. a closed curve showing the variation of the magnetic flux density of a ferromagnetic material with the external magnetic field producing it, when this field is changed through a complete cycle.How can permanent magnet lose its magnetism?
Yes, it is possible for a permanent magnet to lose its magnetism. If you heat a magnet up a little bit, it will lose some of its magnetism, but on returning to room temperature [depending on how high it was heated, and on the shape of the magnet itself], full magnetism can be restored.What is the meaning of magnetization?
magnetization. mag·net·i·za·tion. noun. a. The process of making a substance temporarily or permanently magnetic, as by insertion in a magnetic field.What is magnetic saturation in physics?
Seen in some magnetic materials, saturation is the state reached when an increase in applied external magnetic field H cannot increase the magnetization of the material further, so the total magnetic flux density B more or less levels off.Why back EMF is used in DC motor?
Answer: The induced emf developed when the rotating conductors of the armature between the poles of magnet, in a DC motor, cut the magnetic flux, opposes the current flowing through the conductor, when the armature rotates, is called back emf. Its value depends upon the speed of rotation of the armature conductors.What is Demagnetising effect?
Armature reaction has two undesirable effects, either it distorts the main field, or it reduces the main field flux (or both). When the main field gets distorted, it is known as a cross magnetizing effect. And when the main field flux gets reduced, it is known as the demagnetizing effect.How do you stop an armature reaction?
To eliminate armature or rotor reaction or leakage flux (leakage reactance) in an electric rotating machine, a short-circuit coil winding is wound on and through the rotor or an armature core of the machine. The short-circuit coil winding is wound at a right angle to the main coil to exclude any intervention.What are the losses in DC machine?
Losses in DC Machine. The losses that occur in a DC Machine is divided into five basic categories. The various losses are Electrical or Copper losses (I2R losses), Core losses or Iron losses, Brush losses, Mechanical losses, Stray load losses. These losses are explained below in detail.What does the armature do in a DC motor?
In electrical engineering, an armature is the component of an electric machine which carries alternating current. The armature windings conduct AC even on DC machines, due to the commutator action (which periodically reverses current direction) or due to electronic commutation, as in brushless DC motors.What is commutator function?
Function of commutator: To keep the torque on a DC motor from reversing every time the coil moves through the plane perpendicular to the magnetic field, a split-ring device called a commutator is used to reverse the current at that point.What three factors determine the amount of output voltage for a DC generator?
What three factors determine the output voltage of a DC generator? Strength of the magnetic field, length of the wire, speed of cutting action, and the angle of the cutting action. What is residual magnetism? Magnetism that stays on an electromagnetic core after the electric field is turned off.How can the speed of a DC motor be controlled?
Thus, the speed of a DC motor can be controlled in three ways: By varying the supply voltage. By varying the flux, and by varying the current through field winding. By varying the armature voltage, and by varying the armature resistance.Why Interpoles are used in DC machine?
Interpoles are used in DC Machines to reduce the effect of armature reaction and self induction, mainly in winding at commutators,of DC motors. Interpoles are connected in series with armature winding so that as the armature current changes the flux due to interpoles chances accordingly.What is armature resistance of DC motor?
Starting of DC Motors The only component to limit starting current is the armature resistance, which, in most DC motors is a very low value (approximately one ohm or less), as shown in Equation (6-9).How does a generator start?
First, air is blown into the generator until it is compressed; In this way, it starts combustion and causes the generator to start up. Thus, the generator starts to produce the necessary electrical energy to be distributed according to the needs of the equipment connected to it or the place / space that it will supply.What causes the armature to rotate in a simple motor?
The armature is mounted on bearings and is free to rotate. It is mounted in the magnetic field produced by permanent magnets or current passing through coils of wire, these being termed the field coils. When a current passes through the armature coil, forces act on the coil leading to rotation. 
