Isolators

An isolator is a switchgear device which is used to isolate a part of electric circuit from the remaining circuitry. Isolators are also known as disconnectors. Isolation is essential for any electric circuit during power source identification, busbars selection, changeover and during maintenance. Isolators are not automatic devices and they carry continuous rated current. Isolators do not have current breaking capacity. Different types of isolators are knife blade indoor isolator, sliding contact indoor isolator, centre post-rotating outdoor isolator, double pole-rotating outdoor isolator, pantograph outdoors isolator, rocking or tilting isolator and single break isolator. Manual operation is employed in knife blade indoor isolator. Both moving and fixed contacts are fitted here. A shaft carrying the moving contacts is undergoing rotation with the help of a lever. Contact pressure is maintained by springs. Sliding contact indoor isolator is having longer mechanical life, high fault current capacity and less maintenance is required. This type of isolator consists of moving and fixed contacts, connection pads, jacket insulators, transfer contact, arc extinction chamber, metal cap, cast iron insulator, arcing ring, insulated arm, tubular contact, secondary contact and its rod, base frame and a discharge opening. Centre post-rotating outdoors isolator which is also known as ‘double break type isolator’ is a compact isolator. Contact plate and a switchblade are are fixed with contact assembly in double pole-rotating outdoor isolator. Pantograph outdoors isolator consists of scissors-shaped copper tube, conducting joints and pantograph contact. By integrating the combination of isolators and dropout fuses, we can construct rocking or tilting isolators. Single-break insulator consists off two insulator posts mounted on two poles of which one is fixed and the other one is free to rotate.