# Rogowski coil current sensor

Canonical URL: https://eloragrid.ai/symbols/rogowski-coil
Publisher: Elora Grid
Updated: 2026-10-28
Lookup label: RC
Drawing use: SLD, Schematic
Reference families: IEC, Manufacturer

Air-cored coil around a conductor whose output voltage is proportional to the rate of change of current.

## In plain English

### What does Rogowski coil current sensor mean?

A Rogowski coil is wound on a non-magnetic former and placed around the conductor. Its output voltage is proportional to the rate of change of current, so an integrator in the relay or meter reconstructs the current waveform. With no iron core it does not saturate, which suits high fault currents and wide measuring ranges.

### A simple example

The output is a low-level voltage, not a current, so it must go to an input designed for it and cannot be wired into a conventional 1 A or 5 A CT circuit. The symbol does not show the sensor's coefficient, cable length limits or the matching relay input, all of which affect accuracy.

### What the drawings help you do

Confirm the receiving input is designed for Rogowski sensors. Do not apply CT shorting practice to this low-level voltage output. A Rogowski coil has no iron core and gives a voltage output; a conventional CT has an iron core and a current output.

### This particular reference

Air-cored coil around a conductor whose output voltage is proportional to the rate of change of current. A Rogowski coil has no iron core and gives a voltage output; a conventional CT has an iron core and a current output.

### Terms

- Normally open / normally closed: The contact state in the normal condition defined for the drawing.
- Coil: A wound conductor that can produce a magnetic field when energised.
- Terminal: An identified point where a conductor connects.

Concept diagram: Identify the device and form → Read the connections and state → Check the equipment reference
A guide to reading this reference. The original symbol illustration and its drawing notes appear below; these boxes are not a wiring diagram.

- [Medium-voltage indoor sensors: Rogowski coil and voltage divider low-power instrument transformers](https://www.abb.com/global/en/areas/electrification/medium-voltage/grid-components/core-components/indoor-sensors)
- [Indoor current and voltage transformers](https://www.abb.com/gb/en/areas/electrification/medium-voltage/grid-components/core-components/indoor-instrument-transformers)


## What it represents

A Rogowski coil is wound on a non-magnetic former and placed around the conductor. Its output voltage is proportional to the rate of change of current, so an integrator in the relay or meter reconstructs the current waveform. With no iron core it does not saturate, which suits high fault currents and wide measuring ranges.
The output is a low-level voltage, not a current, so it must go to an input designed for it and cannot be wired into a conventional 1 A or 5 A CT circuit. The symbol does not show the sensor's coefficient, cable length limits or the matching relay input, all of which affect accuracy.

## How to read it

- Confirm the receiving input is designed for Rogowski sensors.
- Do not apply CT shorting practice to this low-level voltage output.

## Information to show or reference

- State sensor coefficient
- Reference matching input
- Respect cable length limit

## Important distinction

A Rogowski coil has no iron core and gives a voltage output; a conventional CT has an iron core and a current output.

## Facts

- Output: Voltage proportional to di/dt
- Saturation: None, as there is no iron core
- Preview: Functional illustration of the device role; not a product footprint or certified standard graphic

## Public references

- [Medium-voltage indoor sensors: Rogowski coil and voltage divider low-power instrument transformers](https://www.abb.com/global/en/areas/electrification/medium-voltage/grid-components/core-components/indoor-sensors) — ABB. Public manufacturer page describing low-power instrument transformers based on Rogowski coils and voltage dividers.
- [Indoor current and voltage transformers](https://www.abb.com/gb/en/areas/electrification/medium-voltage/grid-components/core-components/indoor-instrument-transformers) — ABB. Public manufacturer overview of indoor current and voltage instrument transformers.

## Graphic scope

Independent original educational concept illustration by Elora Grid. Not a certified standards graphic or manufacturer footprint. Unitless; not to scale. Original artwork licence: https://creativecommons.org/licenses/by/4.0/. Publisher material is linked only.