To Investigate Environmental effects of HVDC versus HVAC Transmission Systems

Alternating current (AC) has few drawbacks which have increased the demand of Direct current (DC) Transmission. The normal HVAC range is between 220-800 kV .This high voltage has to pass different types of terrains including settled area, mountains and water. It is quite clear that human beings and environment will be effected from this huge voltage. The common effects of these huge voltages are magnetic fields, electric fields, corona effects, RF interference, acoustic noise, and electromagnetic interference. This paper discusses the technical details of high voltage DC (HVDC) transmission versus high voltage AC (HVAC) transmission in terms of environmental effectson people and surrounding.. Due to generation of electricity, Electric and magnetic fields (EMF) are created. Magnetic fields and Electric fields are formed due to motion and presence of electric charges .These time varying fields are influenced by number of parameters such as magnitude, phase frequency and direction. Electric transmission is basically the transfer of electrical power in bulk form from generating units to substations located near to Load centers. The interconnection of Transmission lines forms together HVAC transmission networks. The transmission Network is named as "power grids" in the USA, while in the UK these networks is called "national grid." It is a usual practice to step up voltage above 110 kV in order to reduce the loss in energy during far away transmission. An electromagnetic field consists of electric and the magnetic fields. The electric field does not depends on the amount of current flowing through conductors but depends on potential difference between charge-carrying bodies where as magnetic field has a relation with the amount of electric current passing through the conductor irrespective of the presence of voltage. Electric field strength is normally measured in (Volt/meter) or in kv per meter (1 kilovolt/meter = 1000 V/m). Magnetic fields are normally represented by magnetic flux density (B) or magnetic field strength (H); both have a direct proportion to the magnitude of the current. B is calculated in the centimeter-gram-second unit, the gauss (G), or the unit of the System International (SI), the tesla (T); 1 mG = 1 x 10 -3