Study of transient current measurement using micro-CAP circuit simulator

The article discusses a novel method of simulation of current transformers using Micro-CAP software package. The Micro-CAP simulator allows using electric and magnetic equivalent circuits of the current transformer for simulation of electromagnetic transients occurring in various operating modes of protective relays. The main advantages of the Micro-CAP program in terms of simulation of measurement current transformers were shown. The article includes recommendations concerning determination of parameters necessary for simulation with the proposed method. It also presents results of a transient simulation for current transformers with a non-linear core. Basing on analysis of simulation model operation and data obtained, a well-justified conclusion may be drawn that current transformers are futureless as primary current transducers for protective relaying applications.