Analysis of factors which influence the application, operation, and design of shunt-capacitor equipments switched in large banks

J. E. Hobson and W. H. Cuttino (non-member; both of Westinghouse Electric and Manufacturing Company, East Pittsburgh, Pa.): Mr. Butler´s paper is of considerable interest at the present time since there is a definite trend toward the installation of large capacitor banks often arranged for separate switching of sections automatically controlled by voltage, current, or power-factor variations. Although the number of large banks installed with automatic switching equipment within the last ten years has been very small compared to the total installations of capacitors, yet the activity in this field is expected to increase considerably due to the increasing number of capacitors being applied on distribution circuits. As a typical example, quite recently a 1,350-kva bank was installed on a distribution bus, 4 kv, to be automatically switched in and out of the circuit in sections of 450 kva, the switching being initiated by voltage changes on the bus. After a careful study of the switching currents which might be expected in this installation, a small amount of impedance was added to each bank to limit the transient equalizing currents.