CT
Current transformer
A current-measurement transformer used with metering and protection equipment.
SLD / Schematic
Symbols · U RES
Residual-voltage monitoring relay
A residual-voltage relay responds to the specified residual-voltage measurement.
SLD / Schematic · U RES
What it represents
A residual-voltage relay responds to the specified residual-voltage measurement. Its drawing needs the voltage-transformer connection and the input quantity definition.
How to read it
- Check the measurement circuit that produces the residual voltage.
- The preview is an original explanation of this function. Match the actual drawing convention to its legend and the selected equipment documentation.
Information to show or reference
- Show VT connection
- State residual input scaling
- Reference operating threshold
A distinction that matters
Residual voltage is different from phase-to-neutral voltage at an arbitrary single phase.
Sources you can follow
These public references support the explanation and provide further detail. Their graphics and downloadable files remain with their publishers.
AutoCAD Electrical: Voltage monitoring relays
Public documentation of this equipment function or named vendor variant; the illustration is independently authored and is not the source graphic.
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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