Electrical on line

                       In a Nominal T model of a  medium transmission line , the series impedance is divided into two equal parts, while the shunt admittance is concentrated at the centre of the line. The nominal T model of a medium transmission line is shown in the figure.                                         Here, Series impedance of the line Z = R + jX Shunt admittance of the line Y = jwc Receiving end voltage = V r Receiving end current = I r Current in the capacitor = I ab Sending end voltage = V s Sending end current = I s                       Sending end voltage and current can be obtained by application of KVL and KCL. to the circuit shown below Current in the capacitor can be given as,            By Kirchoff’s current law at node a, or By Kirchoff’s voltage law Equation of Sending end voltage V s  and current I s  can be written in the matrix form as Also, Hence, the ABCD constant of the nominal T-circuit model of a medium line are The phasor diagram of the nominal T-circu

 1. Length wise classification of transmission line: Short transmission line (l < 80km) Medium transmissio line (80km < l < 250km) Long transmission line (l > 250km) Short transmission line:                       Transmission lines which are having length less than 80 km and operating voltage lower than 20 kV are called short transmission line. Medium transmission line:                       Transmission lines which are having length between 80 km to 250 km and line voltage between 20 kV to 100 kV are called medium transmission line. Long transmission line:                       Transmission lines which are having length above 250 kilometre and line voltage above 100 kilo volt are called long transmission line. 2. Regulation of transmission line:                       Regulation of a transmission line is defined as the change in voltage at the receiving end from no load to full load, the sending end voltage remaining the same. It is usually expressed as a percentage of rece

Light Emitting Diode The LED is a PN-junction diode which emits light when an electric current passes through it in the forward direction. The electron from the N-side and the hole from the P-side are combined and gives the energy in the form of heat and light.  The LED is made of semiconductor material which is colourless, and the light is radiated through the junction of the diode. C onstruction of LED The semiconductor material used in LED is Gallium Arsenide (GaAs), Gallium Phosphide (GaP) or Gallium Arsenide Phosphide (GaAsP). Any of the above-mentioned compounds can be used for the construction of LED, but the colour of radiated light changes with the change in material. Below are some of the material and their respective colour of light which they emit.  Working of LED The electrons are majority carriers in N-type and holes are majority carriers in P-type. The electrons of N-type are in the conduction band and holes of P-type are in the valence band. The energy level of the Cond