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Let n be the number of free electron available per cubic metre of the conductor material. Let v be the axial drift velocity. In time dt, distance travelled would be vdt . If A is the cross section of the conductor, then the volume is vAdt . If e is the charge of each electron  then total charge which crosses the section in time dt is dq=nAev.dt. Since current is the rate of flow of charge, it is given as i=dq/dt=(neAv.dt)/dt i=venA Current density, J=i/A=vne Ampere/m2. Normal J for copper conductor= 1.55 x 10^6 A/m2, n=10^29, e=1.6x10^-19 coulomb, v=9.7 x 10^-5 m/s = 0.58 cm/min.

The concept of Electrical grid was given by Nicole Tesla about 120 years ago. Since then the generation, transmission and distribution of Electrical energy has undergone vast changes. Giant size generators and EHV lines are very common now. The per capita consumption has increased manifold (and is still increasing) and consumers demand reliability and quality in Electric supply. The power industry is faced with challenges and opportunity of transforming the Electrical grid into smart grid to manage demand growth, conserve Energy, reduced losses, optimize efficiency, improve power quality and reliability. Smart grid also known as intelligent grid refers to combination of hardware, software and communication tools to meet the above objectives. The main features of a smart grid are: 1. It is self healing from power distuebances. 2. It ensures power quality and reliability. 3. It accommdates centralized giant size generators as well as distributed generation. 4. It uses conven...

Learning Objectives 1. Working Principle of Transformer 2. Construction Details 3. EMF Equation of Transformer 4. Voltage Transformation Ratio 5. Losses in Transformer 6. No Load and on load operation 7. Testing of Transformation 8. Efficiency and Voltage Regulation 9. Kapp Regulation Diagram 10. Auto Transformer 11. Instrumental Transformer (C.T and P.T)