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 · LPCT
Low-power current transformer
Small iron-core CT with an integral shunt that delivers a low-level voltage signal instead of a standard secondary current.
In plain English
What does Low-power current transformer mean?
A low-power CT uses a small magnetic core and an integral burden resistor, so its output is a low-level voltage proportional to primary current. It suits digital relays and compact switchgear, and a single LPCT can often replace several conventional CT ratios.
A simple example
Because the burden is built in, the output must not be shorted or loaded like a conventional CT, and it cannot feed electromechanical relays or ordinary meters. The symbol shows the sensor but the reader must confirm the relay input type and the sensor's rated output.
What the drawings help you do
Check the receiving input is an LPCT input. Do not short the output as for a conventional CT. An LPCT has an iron core with integral burden; a Rogowski coil has no iron core and gives a di/dt output.
This particular reference
Small iron-core CT with an integral shunt that delivers a low-level voltage signal instead of a standard secondary current. An LPCT has an iron core with integral burden; a Rogowski coil has no iron core and gives a di/dt output.
- Winding
- A coil of conductor inside an electrical machine or transformer.
- Coil
- A wound conductor that can produce a magnetic field when energised.
- Signal
- Electrical information passed between devices, rather than necessarily the main power supply.
Read the source: Medium-voltage indoor sensors: Rogowski coil and voltage divider low-power instrument transformers · Indoor current and voltage transformers
SLD / Schematic · LPCT
What it represents
A low-power CT uses a small magnetic core and an integral burden resistor, so its output is a low-level voltage proportional to primary current. It suits digital relays and compact switchgear, and a single LPCT can often replace several conventional CT ratios.
Because the burden is built in, the output must not be shorted or loaded like a conventional CT, and it cannot feed electromechanical relays or ordinary meters. The symbol shows the sensor but the reader must confirm the relay input type and the sensor's rated output.
How to read it
- Check the receiving input is an LPCT input.
- Do not short the output as for a conventional CT.
Information to show or reference
- State rated output
- Reference relay input type
- Show sensor cable
A distinction that matters
An LPCT has an iron core with integral burden; a Rogowski coil has no iron core and gives a di/dt output.
Sources you can follow
These public references support the explanation and provide further detail. Their graphics and downloadable files remain with their publishers.
Medium-voltage indoor sensors: Rogowski coil and voltage divider low-power instrument transformers
Public manufacturer page describing low-power instrument transformers based on Rogowski coils and voltage dividers.
Indoor current and voltage transformers
Public manufacturer overview of indoor current and voltage instrument transformers.
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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