Wednesday, September 10th, 2008
Magnetic systems could be of two types they are singly exited and multiply exited magnetic systems.
In singly exited magnetic systems usually one electrical source is employed.It is generally used to attract or repel hence to make devices like relays,electromagnets etc.
Single Excited Electromagnetic System
Let us look how an energy build up happens in a single exited electromagnetic system.
Suppose in a relay if we are giving electrical energy the static part gets magnetized and attracts the movable armature to it hence a part of that magnetic energy is converted into mechanical energy.so
Electrical energy input = mechanical energy output + increase in field energy
The above equation is based on the assumption that there is magnetic core loss in the conductor and no leakage flux.The read more
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Wednesday, September 10th, 2008
The phenomenon by which an emf is induced in a conductor when it is cut by magnetic flux is known as electromagnetic induction.
Faraday’s First Law
It states that,When ever a conductor cuts a magnetic field or viceversa an emf is induced in it and it setsup in such a direction so as to oppose the cause of it.
Faraday’s second law
It states that the magnitude of induced emf is equal to the rate of change of flux linkage.
Mathematically
e = -NdØ/dt
e – induced emf
N- number of turns of coil
dØ/dt – rate of change of flux
the minus sign represents that the induced emf or current sets up in a direction so as to oppose the cause of it.
Induced emf
Induced emf could be classified into dynamically induced emf and statically induced emf.
Dynamically induced emf
This is the emf induced read more
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Wednesday, September 10th, 2008
The advantageof electrical energyover other energies is that it could be transmitted over a long distance without much loss and with highefficiency.The devices which convert electrical energy into other forms of energy is known as electromechanical devices and the process is known as electromechanical energy conversion.The conversion takes place through either electrical or magnetic medium surrounding the device.The electromechanical devices could be classified into three categories primary ,secondary and tertiary.Primary includes the continuous energy conversion elements such as motors,generators etc ie the linear and rotating electrical machines.The second category includes transducers which could work on with even very small input and the tertiary the force producing devices like read more
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