Connection of Shunt Capacitors at Distribution Transformer
Provision of capacitors at load point is found to be hard in practice because of the additional investments needed. It has also been experienced in which the LT motive power consumers do not ensure the working of capacitors even if these are given at the time of release of connections. The agricultural consumers are not keen to improve the power factor of their motors, as they are not benefited because of flat rate tariff. Further, the consumers do not have requisite knowledge and skill to decide the level of compensation and check the availability.
Although planning the distribution systems, such local practical problems could be taken care of through the power utilities by giving LT capacitors on distribution transformers. Switched or fixed capacitors at the distribution transformer are the further best alternative. The shunt capacitor supplies constant reactive power at its location, independent of the load. Thus, optimal compensation given for peak load condition might result in over compensation during light load conditions, necessitating automatic switching schemes.
Fixed capacitors are suitably selected for light load conditions and linked permanently. The automatic switched capacitor bank of rating appropriate for maximum kVA requirement of the concerned distribution system is installed along with essential provision of switching to suit the reactive demand of the system at any particular time. The switched capacitors could be switched off in steps and brought back in service as the reactive load on the system raise.