RC
Rogowski coil current sensor
Air-cored coil around a conductor whose output voltage is proportional to the rate of change of current.
SLD / Schematic
Symbols · OCT
Optical current sensor
Current sensor using light in an optical fibre around the conductor, whose polarisation changes with the magnetic field.
In plain English
What does Optical current sensor mean?
An optical current sensor measures current from the rotation of polarised light in a fibre wound around the conductor, a magneto-optic effect proportional to the enclosed magnetic field. It is used in higher-voltage and DC applications where conventional CTs are bulky or where saturation and insulation are concerns.
A simple example
The sensor head connects through fibre to an electronics unit, which usually outputs digital sampled values to protection and metering devices. The symbol does not show the electronics unit, its supply or the data interface, all of which must be drawn for the measurement chain to be complete.
What the drawings help you do
Find the electronics unit that converts the optical signal. Check the data interface to protection devices. An optical current sensor uses light in fibre; a conventional CT uses magnetic induction in a winding.
This particular reference
Current sensor using light in an optical fibre around the conductor, whose polarisation changes with the magnetic field. An optical current sensor uses light in fibre; a conventional CT uses magnetic induction in a winding.
- DC
- Direct current: electricity flowing in one direction.
- Signal
- Electrical information passed between devices, rather than necessarily the main power supply.
- Rating
- A value stating the conditions for which equipment is specified.
Read the source: Indoor current and voltage transformers · IEC graphical symbols for diagrams
SLD · OCT
What it represents
An optical current sensor measures current from the rotation of polarised light in a fibre wound around the conductor, a magneto-optic effect proportional to the enclosed magnetic field. It is used in HV and DC applications where conventional CTs are bulky or where saturation and insulation are concerns.
The sensor head connects through fibre to an electronics unit, which usually outputs digital sampled values to protection and metering devices. The symbol does not show the electronics unit, its supply or the data interface, all of which must be drawn for the measurement chain to be complete.
How to read it
- Find the electronics unit that converts the optical signal.
- Check the data interface to protection devices.
Information to show or reference
- Show sensor head and electronics
- Reference output interface
- State auxiliary supply
A distinction that matters
An optical current sensor uses light in fibre; a conventional CT uses magnetic induction in a winding.
Sources you can follow
These public references support the explanation and provide further detail. Their graphics and downloadable files remain with their publishers.
Indoor current and voltage transformers
Public manufacturer overview of indoor current and voltage instrument transformers.
IEC graphical symbols for diagrams
IEC context for graphical symbols used in diagrams; no IEC graphic is reproduced.
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.
Explore related references
Put the reference into a drawing workflow.
Elora Grid helps electrical teams work with drawings, specifications and equipment information. Explore the drafting workflow or join the early-access waitlist.