Their role is to induce a proportional smaller current from high-current cables for metering and relay protection purposes. Some panels may contain only one CT, while others might have five. Primary distribution systems consist of feeders that deliver power from distribution substations to distribution transformers. Many feeders leave substation in a concrete ducts and are routed to a nearby pole. At this. A current transformer (CT) is a type of transformer that reduces or multiplies alternating current (AC), producing a current in its secondary which is proportional to the current in its primary. Its application scenarios include: Expanded single-phase meter range: The meter range can be expanded to meet specific needs by connecting to a single. secondary unit substation is a close-coupled assembly consisting of enclosed primary high voltage equipment, three-phase power transformers, and enclosed secondary low-voltage equipment.