Current-limiting reactors

These are high inductances which are used to limit current or power. Here reactive power compensation is taking place which improves the power factor of the network and brings the system voltage within the specified limit. The four types of reactors which are in use are dry air-cored reactor, oil-immersed reactor (magnetically shielded and non-magnetically shielded) and saturated reactor. In all the reactors, design is such that the reactor core does not get saturated even if the fault current reaches the highest value. Here shield is made up of a ferromagnetic material. Dry air-cored reactor is a simple reactor which is unshielded and executed in the open. Reactor is cooled either by natural air circulation or by forced air circulation. A frame made of synthetic resin glass reinforced supports the reactor and a wooden frame supports the cylindrical coil. Here inductance is very low. In oil immersed, non-magnetically shielded reactor, the tank is filled with transformer oil. This oil carry coil without an iron core. Coil and tank are separated by a cylindrical-shaped aluminium layer. In magnetically shielded oil-immersed reactor, laminated silicone steel made core is fixed between the coil and the steel tank. The use of saturated reactor is in the short circuit limiting coupling circuit.