VT / PT
Voltage transformer
A transformer providing a voltage signal for metering or protection.
SLD / Schematic
Symbols · CT
Current transformer
A current-measurement transformer used with metering and protection equipment.
SLD / Schematic · CT
What it represents
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.
On a single line diagram, the CT is placed at the measurement location. A schematic expands the secondary wiring, terminals and connected devices. Multi-core and multi-secondary CT arrangements require additional information; one generic preview cannot describe every configuration.
How to read it
- Follow the primary conductor through the CT and then identify the secondary circuit separately.
- Polarity marks and terminal labels belong to the selected device and its documented connections.
Information to show or reference
- Identify the metering or protection purpose.
- Reference the ratio, class and burden in the equipment documentation.
- Cross-reference secondary terminals and any test facility.
A distinction that matters
A CT measures current. A VT measures voltage. Their secondary circuits and isolation/testing arrangements are different.
Sources you can follow
These public references support the explanation and provide further detail. Their graphics and downloadable files remain with their publishers.
Current transformer symbol variants
Public CT symbol categories and secondary-winding variants.
Indoor current and voltage transformers
Manufacturer examples of current and voltage transformers.
Transformer terminals for measuring and test circuits
Manufacturer reference for CT test-terminal arrangements.
About this graphic
This illustration was authored independently by Elora Grid to explain the concept. It is not reproduced from a customer drawing, an official standard graphic or a manufacturer CAD file. Its correspondence to an exact IEC or IEEE symbol identifier has not been certified.
SVG and DXF downloads contain this original artwork. DXF uses unscaled drawing units; a GA envelope supplies no product dimensions, clearances or fabrication information. Original artwork is available under CC BY 4.0. Third-party references retain their own terms.
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