Side-by-side reference

Understand the difference.

Compare the meaning, drawing context and source references of two entries. A similar graphic or shared abbreviation does not establish equivalence.

First referenceCompare with

CT/VT

Symbols

Combined instrument transformer

A combined instrument transformer places a CT and a VT in one insulated housing for each phase. It saves space and foundations at outdoor HV metering points and appears in MV metering units where the supply authority needs both current and voltage for a billing meter.

Drawing use: SLD / Schematic
Application: Metering & protection
Reference family: IEC / Manufacturer

A distinction that matters

A combined instrument transformer houses a CT and VT together; separate units are drawn and specified independently.

Full reference

Symbols

Current transformer

A current transformer produces a secondary current related to the current in its primary conductor. A drawing uses the CT representation to show where current is measured and which metering or protection circuit receives that measurement. It does not, by itself, specify the CT ratio, accuracy class, burden or secondary connection.

Drawing use: SLD / Schematic
Application: Metering & protection
Reference family: IEC / IEEE / ANSI

A distinction that matters

A CT measures current. A VT measures voltage. Their secondary circuits and isolation/testing arrangements are different.

Full reference

Original educational previews. Follow the source references on each full entry for the appropriate standard or selected product.