The basic principle of resistance heating is that, when current passes through some resistance, power loss takes place which appears in the form of heat. There are two types of resistance heating, namely, direct resistance heating and indirect resistance heating. Direct Resistance Heating In the direct resistance heating, the electric current passes through the charge […]
The supporting structure for overhead lines is required to keep the bare conductors at a suitable level above the ground. These may be various types of poles or towers. They should have following essential properties: Types of Poles in Transmission Line The following are main types of poles and towers generally used in the overhead
The overhead line conductors are supported on the poles or towers. In order to prevent the flow of current to earth through supports, the line conductors must be properly insulated from supports. This is achieved by securing line conductors to supports with the help of overhead line insulators. These insulators provide necessary insulation between the line
The cost of conductor material is a vital part of the total cost of a transmission line. Therefore, the calculation of the conductor size of a transmission line is very important. The economic size of conductor is determined by Kelvin’s law. It is used to find out the most economical area of x-section of a
The transmission of electric power over long distances was developed at the beginning of the twentieth century. Since then, it has made rapid progress in its design and methods of operation, which has resulted in greater reliability and continuity. The electric power can be transmitted either by means of an AC or DC system. Each
The hysteresis motor is well known for its noiseless operation. Therefore it is generically used in audio recording-related equipment. In this article, I am discussing the working principle of hysteresis motor. It is a single-phase motor whose operation depends upon the hysteresis effect i.e. magnetization produced in a ferromagnetic material lags behind the magnetizing force.
A universal motor is a modified form of a DC series motor and is widely used in home appliances like mixers and machine tools. In this article, I am discussing the universal motor working principle. The construction of universal motor is very similar to a two-pole DC series motor. It consists of two field coils wound on a
A capacitor motor is also a split-phase induction motor. In this motor, starting winding has a capacitor in series with it. To start the motor, the necessary phase difference between both windings currents is produced by connecting a capacitor in series with it. This is improved form of split phase motor. This type of motor
A split phase motor is provided with an auxiliary stator winding called starting winding in addition to main or running winding. These windings are placed in the stator slots. Both the windings are put in parallel. The purpose is to get two different currents sufficiently displaced in phase from each other so that a revolving
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A mechanical resonance type frequency meter indicate the supply frequency of the circuit directly and is very much convenient for most practical purposes. It is a very simple instrument and has got an advantage of giving reading free from errors due to change in temperature, waveform and magnitude of applied voltage. Construction of Mechanical Resonance Type