The speed of an induction motor can be controlled by two major methods. They are: Stator side control Rotor side control The first method is applicable for both squirrel-cage and wound-rotor motors. The second method can be used only for wound-rotor motors. Stator side control means, we have to vary the stator side parameters, supply
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When 3- Φ Induction motor is switched on at normal supply voltage, heavy current “ill flow through the motor because at the time of starting, there is no back emf. An induction motor, when directly switched on, takes five to seven times its full load current and it develops only 1.5 to 2.5 times full load
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Three phase induction motors are extensively used for electric drives. The main advantages which make it so popular for industrial use are: It is simple and extremely rugged construction. High reliability. Low cost. Its ability to start off from rest unlike synchronous motors which have to be started and run up by separate prime movers.
Three Phase Induction Motors – Introduction Read More »
The generation of electric power is three-phase in nature and the generated voltage is 13.2kV, 22kV or higher. Transmission of power is carried out at high voltages like 132kV or 400kV. Before transmission, it is required to step-up the voltage and for this a thee phase step-up transformer is required. Similarly, at the distribution sub-station
Three Phase Transformer Connections – Pedagogy Zone Read More »
The ordinary or commercial efficiency of a transformer is defined as the ratio of output power to the input power. [latex] \% \text { of Commerical Efficiency }=\frac{\text { Output Power }}{\text { Input Power }} \times 100 \wedge [/latex] There are certain types of transformers whose performance can not be judged by this efficiency.
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Rating of a Transformer The name plate of a transformer specifies the rated voltages of primary and secondary windings, the rated currents of primary and secondary windings and the rated volt-amp. Meanings of these specifications are as under: While manufacturing a transformer, insulations are provided to primary and secondary windings. These insulations are such that
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Consider a transformer arrangement as shown in figure. N1– Number of primary turns N2 – Number of secondary turns Φm – Maximum value of flux in the core in wb Bm – Maximum value of flux density in the core in wb/m² A – Area of the core in m² f – Frequency of the
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Construction Details A transformer is a static device and its construction is simple as there are no moving parts. The main components of a transformer are The magnetic core. Primary and secondary windings. Insulation of windings. Expansion tank or conservator. Lead and tappings for coils with their supports, terminals and terminal insulators. Tank, oil, cooling
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Transformer works on the principle of electromagnetic induction. A transformer is an electrical device, having no moving parts, which by mutual induction transfers electric energy from one circuit to another at the same frequency, usually with changed values of voltage and current. It consists of two windings insulated from each other and wound on a
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In practice it is often required to stop a unit driven by dc motors in an exact position or to have the speed of the driven unit suitably controlled during its deceleration. Such requirement is satisfactorily fulfilled by electric braking. Types Regenerative braking Counter-current braking or plugging Dynamic braking Regenerative Braking Regenerative braking with return
Electrical Braking of D.C Motor, Types Read More »