Cost-effective differential protection for transformers with up to 6 sets of CTs The T35 is designed to provide basic transformer protection functions for variety of transformer applications. It uses multiple current inputs to provide primary protection and backup protection of transformers, including differential, phase and ground overcurrent. The relay can be configured to accept up to 6 sets of current inputs to provide proper differential restraint for applications with three-winding transformers with windings configured in dual-breaker arrangements.