CT and VT functions
A current transformer (CT) reproduces primary current at a lower, defined secondary current. A voltage transformer (VT), also called a potential transformer, provides a scaled voltage signal for connected instruments and protection devices.
Measurement and protection
Instrument transformers supply meters, protection relays and monitoring systems in substations, industrial installations and renewable energy plants. Ratio, accuracy class and rated burden must match the intended function.
Important circuit distinctions
An energized conventional CT secondary must not be left open-circuit. A VT secondary must be protected against short circuits. Secondary circuit design, grounding and protection require the correct equipment documentation.