CT Saturation In Industrial Applications - Analysis and Application Guidelines

This paper explains issues associated with instantaneous overcurrent protection in industrial applications where protective relays may be supplied from low-ratio CTs. The problem is analyzed in detail, and its underlying mechanics explained. A formal, compact and easy to grasp method is shown to present complex relations between the CT response and the response of any given relay. Based on this graphical method one can quickly evaluate the problem and clearly see alternative solutions if a problem truly exists.