A combined instrument transformer primarily consists of a voltage transformer and a current transformer mounted on a common framework to form an integrated unit. While internal structures vary slightly depending on the insulation method, the core components remain essentially the same.
1. Core and Windings: Voltage transformers typically utilize an external-core design with silicon steel laminations, whereas current transformers mostly employ an internal-core design; both feature primary and secondary windings.
2. Framework and Leads: All components are mounted on a steel framework, with the leads from the primary and secondary windings routed outward to connect to high- and low-voltage insulators or porcelain bushings located on the exterior of the housing.
3. Terminals: Terminal blocks are provided on the exterior of the housing for connection to power supply lines and metering instruments.
