CHAPTER 3 MISCELLANEOUS 3.1 BATTERIES: - In electrical power stations and large capacity substations, the operating and automatic control circuits, the protective relay systems, as well as emergency lightning circuits, are supplied by station batteries. The latter constitute independent source of operative dc power and guarantee operation of the above mentioned circuit irrespective of any fault which has occurred in the station or substation, even in the event of complete disappearance of the ac supply in the installation. Station batteries are assembled of a certain number of accumulator cells depending on the operating voltage of the respective dc circuits. Storage batteries are of two types namely lead acid and alkaline batteries are most commonly used in power stations and substations because of their higher cell voltage and low cost. Detailed description of the storage batteries is beyond the scope of the book and for it, A course in electrical technology volume 1of the same au...