Current Transformers with Linear Cores.

Conventional cores of current transformers used in protective schemes are only capable of transmitting non-displaced fault currents satisfactorily if these are below the multiple of the rated current characterized by the overcurrent factor. In the case of artificially-displaced fault currents with dc component decaying initially according to an exponential function, the cores of such current transformers become very quickly saturated and, consequently, disturb the functioning of the protective gear connected to the current transformer. This disadvantage has been offset by increasing the size of the cores and introducing a number of air gaps. The parameters influencing the design of the linear cores, which are being used to an ever-increasing extent for generator protection and protective gear in high-voltage systems, are discussed.