Electric resistance welding is a group of welding processes in which welding heat is obtained from resistance of the work to the flow of electrical current and by application of pressure. No flux or filler metal is added. Working Principle of Electric Resistance Welding In resistance welding, a heavy current above 100 A at low […]
An ideal transformer is one which has no losses (no iron loss and no copper loss) and no leakage flux i.e. all the flux produced by the primary winding is linking with the secondary winding. In actual practice, it is impossible to make such a transformerbut to understand the concepts of transformer it is better to
The most important parts used in the three phase transformer are windings and core. Some other parts such as a tank, conservator, bushing, breather etc. are also used along with the core and windings. Simplified construction of a three phase transformer is shown in the figure. Parts of Three Phase Transformer Laminated Steel Core: The
The electrical energy generated at the power stations is conveyed to the consumers through a network of transmission and distribution systems. In the power system, the electrical energy generated at the power stations is conveyed to major sub-stations. From the major sub-stations, it is conveyed to the bulk power consumers by high voltage distribution system
Corona Effect in Transmission Lines It can be noticed that near the overhead lines, there exists a hissing noise and sometimes a faint violet glow. The effect due to which such phenomenon exists surrounding the overhead lines is called the corona effect. When a normal alternating voltage is applied across two conductors with enough spacing
When the load is supplied there are line losses due to the resistance of the line conductors. Therefore, the power received at receiving end is always less than the sending end voltage. Efficiency of Transmission Line The ratio of receiving end power to the sending end power of a transmission line is called the transmission
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A steady direct current flowing through the conductors is uniformly distributed over the whole cross-section of the conductor. However, an alternating current flowing through the conductor does not distribute uniformly, rather it tends to concentrate near the surface of the conductor as shown in the figure. This is known as skin effect in transmission line.
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The ordinary squirrel cage induction motor has excellent running characteristics, but it suffers from the drawback that due to its very low rotor resistance, it’s starting torque is poor. The starting torque can be improved by increasing the rotor resistance but in case of squirrel cage induction motor external resistance can’t be added in the rotor
Speed Control of 3 Phase Induction Motor A 3-phase induction motor is practically a constant-speed machine. The speed regulation of an induction motor (having low resistance) is usually less than 5% at full-load. In these motors, speed reduction is accompanied by a corresponding loss of efficiency and much speed regulation. Different methods by which speed
The various starting methods of induction motor which are employed to restrict the initial rush of current in squirrel cage induction motors are given below: Starting Method of Induction Motor Direct on Line Starting Method of Induction Motor In this starting method of induction motor, the motor is switched on direct to the supply mains