Electrical engineering

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

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.

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

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

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

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

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

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

There are several forms of braking applicable to the usual types of electric motors. Generally, we can group all electrical braking methods into three types. Regenerative braking Dynamic or Rheostatic braking Plugging or reverse current braking Regenerative braking In the regenerative braking operation, the motor operates as a generator, while it is still connected to