Provide a general description of the protection current transformer (CT) as a component of the overcurrent protection system. Describe the CT in physical and mathematical terms using fundamental laws in their symbolic form. Develop a suitable model of the electrical-circuit configuration of the CT. Obtain a set of symbolic equations in electrical and magnetic variables pertinent to the CT. Solve the set of equations to obtain symbolic functions describing the time-varying parameters. Derive the symbolic functions describing the supplementary time-varying parameters.