The frequency of induced e.m.f in the armature conductors depends upon speed and the number of poles. Let, N = rotor speed in r.p.m P = number of rotor poles. f = frequency of induced e.m.f in Hz. Consider a stator conductor that is successively swept by the N and S poles of the rotor.
Frequency of Induced EMF in Rotor Read More »
An alternator has 3 phase winding on the stator and D.C field winding on the rotor. Stator It is the stationary part of the machine and is built up of sheet-steel laminations having slots, on its inner periphery. A 3 phase winding is placed in these slots and serves. as the armature winding of the
Alternator Construction and Working – Pedagogy Zone Read More »
The machine which produces 3 phase power from mechanical power is called an alternator or synchronous generator. An alternator works on the same fundamental principle of electromagnetic induction as a D.C generator, when the flux linking a conductor changes, an emf is induced in the conductor. Like a D.C generator, an alternator also has an
Introduction of Synchronous Machines – Pedagogy Zone Read More »
The stator winding of a single phase induction motor is connected to single phase AC supply. Then a magnetic field is developed in the stator whose axis is always along the axis of stator windings. With alternating current in the fixed stator coil the mmf wave is stationary in space but pulsates in magnitude and
Operation of Single Phase Induction Motor Read More »
The single phase induction motors are small motors. These motors have power rating in fractional horse power range. These motors are used in homes, offices, shops and factories. They provide motive power for fans, washing machines, hand tools like, drillers, record player, refrigerators, juice makers etc. The single phase motors are simple in construction. The
Single Phase Induction Motors – Introduction Read More »
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
Speed Control of Three Phase Induction Motor Read More »
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
Starting of Three – Phase Induction Motor Read More »
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.
All Day or Energy Efficiency of Transformer Read More »