A Novel Current Injection Transformer with a Self over Current Protection Capability

Current injection transformer (CIT) systems are within the major group of the standard type test of high current equipment in the electrical industry. One of crucial concern in a CIT system is its overcurrent protection. In this paper the principle of self limiting transformers (SLTs) is used as a basis for the conceptual design of a self limiting CIT (SLCIT) system. The design and operation principle of a SLCIT is presented. Unlike the conventional power transformers, the CIT has only one turn in secondary; thus, to make the design of the SLCIT more flexible, auxiliary winding is proposed to be in series with primary winding . Transient FEM simulation of SLCIT is made by simulation is consisted of electromagnetic and thermal part. Since the thermal properties of only the superconductor were proposed, just HTS ring was modeled in the thermal part. While electromagnetic thermal coupling in transient mode is not available directly in Flux, the procedure of the synchronization and data exchange is controlled with Python commands. Field distribution in the core area and current in circuit is analyzed to investigate the performance of the SLCIT. using the software package Flux2D. The