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What is Faraday law of a DC generator?
Faraday's law : If a "conductor" is placed in a "magnetic field" the movement in either conductor or field produces an induced emf in the conductor. In generator the produced torque will be in AC(alternating current) so commutator or slip rings is used to produce unidirectional torque required for production of Direct Current. Basically by Faraday law the produced torque will be always bidirectional, for alternator the bidirectional torque can be used directly. for DC generator the unidirectional torque is needed to produce Direct Current.
What is the difference between a DC motor and a generator in terms of EMF?
During the operation of a DC motor, EMF is created across its terminals using an external source. Whereas, in a DC generator EMF is created across its terminal based on principle of dynamically induced EMF. So talking in terms of EMF, in DC motor EMF is consumed by the motor coil and utilized to rotate the axle. On the other hand, in DC generator EMF developed across coil is transfered to a load or a battery and consumed by them.
What does an increase in field strength in a dc generator causes a?
increased Back emf
Why a dc generator you unable to generate emf even its armature is rotating?
bad connection
What is it mean to say that an alternating current leads or lags an alternating emf?
It is another way of saying that the circuit is capacitive reactive circuit. Look up the mnemonic ELI the ICE man. ELI, voltage leads the current in an inductive circuit. ICE, current leads the voltage in a capacitive circuit.
What is the function of a commutator in DC generator?
All types of generators induce EMF in sinusoidal wave form. (A.C.) In a D.C. generator the function of a commutator is to convert A.C. EMF into D.C. The commutator rectifies the output that is the alternating current so as to produce unidirectional alternating current (pulsating DC). This reverses the negative polarity current to a positive one so as the output is a pulsating DC.
What is the role of a commutator in an electric generator?
The purpose is to counteract the feld distorsion that is caused by the armature current. If this is left as is , the commutation properties of the gnerator will be disturbed, the commutation will not take place in the neutral zone and brush sparking occurs. With correctly sized commutating poles the commutation at the brushes will be in the neutral zone regarless of armature current, no sparking occurs, and a anual adjustment of the brushgear position at different loads is not needed
Can emf induced without an alternating magnetic flux?
No. EMF can only be induced in a wire by a varying magnetic flux. It does not have to be alternating, but it must be varying.
What is Faraday law of a DC generator?
Faraday's law : If a "conductor" is placed in a "magnetic field" the movement in either conductor or field produces an induced emf in the conductor. In generator the produced torque will be in AC(alternating current) so commutator or slip rings is used to produce unidirectional torque required for production of Direct Current. Basically by Faraday law the produced torque will be always bidirectional, for alternator the bidirectional torque can be used directly. for DC generator the unidirectional torque is needed to produce Direct Current.
Operation of DC generator?
1) PRINCIPLE:Whenever a conductor cuts magnetic flux, dynamically induced emf is produced in it. ( Faraday's Laws of Electromagnetic Induction ). This emf causes a current to flow if the conductor circuit is closed.2 ) OPERATION:Field winding produces magnetic field in D.C. generator. Armature is coupled to the prime mover. Prime mover produces torque so the armature rotates. The armature cuts the magnetic field so the emf is induced in the armature. When load is connected to the armature, electric current flows from the armature conductors, through load and back to the armature conductors. Now, as current flows through the armature and it is in the magnetic field, torque is produced due to it. (This torque is called back torque). If the load on the generator is increased, the back torque increases so the torque of the prime mover also increases and the input power to the prime mover increases. In this way, the generator converts mechanical energy into electrical energy.It should be observed that the emf induced in D.C. generator, is A.C. ( so the emf induced in the armature is alternating in nature. ). Then with the help of commutator, it is converted into D.C. Rings and brushes are used to take the emf outside.
What is the difference between a DC motor and a generator in terms of EMF?
During the operation of a DC motor, EMF is created across its terminals using an external source. Whereas, in a DC generator EMF is created across its terminal based on principle of dynamically induced EMF. So talking in terms of EMF, in DC motor EMF is consumed by the motor coil and utilized to rotate the axle. On the other hand, in DC generator EMF developed across coil is transfered to a load or a battery and consumed by them.
What does an increase in field strength in a dc generator causes a?
increased Back emf
What will happen if generator is overexcited?
if a generator is overexcited it is producing a large amount of reactive power which requires an increase in the alternator emf. To produce this emf, the rotor currents must increase resulting in extreme ohmic rotor losses.
What is the relationship between the speed of a generator and its voltage and the torque on the generator shaft and the current produced by the generator?
emf produced by generator(E)=no. of turns in coil*rate of change of magnetic flux
How does a generator use electromagnetic induction?
There is a motor in a generator which carries out this electromagnetic induction,as we switch on the generator the magnetic field lines between that motor get cuts off by the rotating coil which cause change in flux and change in flux cause induced emf,cue to emf at different points of coil cause current to get flow and then generator will get on.
Why a dc generator you unable to generate emf even its armature is rotating?
bad connection
What is it mean to say that an alternating current leads or lags an alternating emf?
It is another way of saying that the circuit is capacitive reactive circuit. Look up the mnemonic ELI the ICE man. ELI, voltage leads the current in an inductive circuit. ICE, current leads the voltage in a capacitive circuit.
