1.0 Introduction
An induction or a synchronous motor is an AC electric motor in which the electric current in the rotor need to produce torgue is included by electromagnetic induction from the magnetic field of the stator winding. An induction motor there fore does not require mechanical commutation, separate excitation or self excitation for all or part of the energy transferred from stator to rotor, as in universal, DC and synchronous motors. An induction motors rotor can be either wound type or queerly cage type.
Three phase squirrel cage induction motors are widely used in industrial drivers because they are rugged, reliable and economical. Single phase induction motors are used extensively for smaller loads, such as house hold appliances like fans. Although traditionally used in fixed speed service, induction motors are increasingly bring used with variable frequency drives (VFDS) in variable speed service. VFDS offer especially important energy savings opportunities for existing and prospective induction motors in variable torque centrifugal fan, pump and compressor load applications. Squirrel cage induction motors are very widely used in both fixed speed and VFDS applications.
Formation of solar cell using semi-conductor material is the act of using a semi-conductor to build a cell that can generate electricity when light (photons) falls on it. in the field of electrical and electronics engineering a semi-conductor simply means those materials whose conductivity lies somewhere between that of pure conductors and insulators. They are neither good conductors nor good insulators at normal room temperature (25oc). They are insulators at very low temperatures and good conductors at high temperature. The Germanium (Ge) and silicon (Si) elements are the most important semi-conductor used in electronics.
A pure type of semi-conductor without doping is called an intrinsic semi-conductor, while extrinsic semiconductor is the one with doping. Where doping is the intentional addition of impurities to semi-conductors so as to increase its conductivity. For instance using silicon. When a silicon is doped with boron the resulting type is P-type, while if with phosphorous the resulting type is N-type. Hence solar cell has two parts the N-type and P-type side. And without this electric field, the cell would not work and this field forms when the N-type and P-type silicon are in contact.
Hence the electrons form the N-type side will rush to fill up the hole in the P-type side. Then when light in form of photons falls on the solar cell the energy frees electrons-hole pairs, with the presence of the electric field the electrons are caused to flow in a particular direction. Hence electric current is provided and the cells electric field causes a voltage flow.
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