High Voltage Engineering - Introduction

Introduction to High Voltage Engineering

    A power system consists of generation, transmission and distribution system. The generating station consists of energy resources, (like hydro, coal, gas, etc.) prime mover, alternator and load.

    The prime mover may be a hydraulic turbine or steam driven turbine or internal combustion engine. This prime mover has to convert one form of energy into rotation of the shaft which in turn drives the, alternator.

    The electrical load on the system may be lighting loads, heating loads or motor loads.

    The control system has to provide constant voltage and to maintain the speed of the machine by excitation control and speed governing mechanism.

    Lightning discharges are the natural form of high voltages. Lightning discharges transfer positive charge upward to restore the system's dynamic balance. The regular current flow between the positively charged ionosphere and the negatively charged earth is controlled by global thunderstorm activity.

    In high voltage transmission, naturally current decreases. So transmission loss I2R decreases and the size of transmission conductor decreases and the cost of copper required also decreases for a long distance. Therefore high voltage is preferred for transmission of long distance.

    For a given power, a H.V requires smaller current and therefore smaller conductor cross-sectional area and lower conductor costs. The current-dependent copper losses are reduced.

    High voltages are used in transmission, so we should generate high voltage. We have to measure such high voltages, so we need high voltage and current measuring devices.

General Applications of High Voltage

High voltage is utilized in:

                                ➢Cathode ray tubes

                                ➢Particle accelerators

                                ➢Xerography

                                ➢Spray painting

                                ➢Electrostatic precipitators

                                ➢Ignition in internal combustion engines

                                ➢ Gas discharge lamps

                                ➢Ozone generators

                                ➢Nuclear research

    To meet the increasing demand for electricity day by day, large power stations are built for efficient utilization of water power, conventional fuel and nuclear fuel. Nowadays 1000 MW being generated in a single power station.

    The demand of electrical energy increases day by day. Therefore the size of the power system increases. We need high generating voltages, to avoid the building cost and operating cost of small power stations. The transmission of voltages should be high to reduce power losses and reduce the cost of transmission.

    For measuring the high generating voltages, we should have high voltage measuring devices and high current measuring devices. The electrical power apparatus like insulators, cables, power transformers, circuit breakers, surge arresters should be designed to withstand such high voltages and high currents. So, we need testing of such devices.

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