M
Three-phase motor
An electrical motor load connected to its switching and protective equipment.
SLD / Schematic
Protection functions · 49
Thermal protection
A thermal protection function for a documented machine or transformer application.
SLD / Schematic · 49
What it represents
A thermal protection function responds to a thermal condition or model appropriate to the selected machine or transformer application. Its inputs and implementation vary between devices, so the number alone does not establish a sensor arrangement or a thermal model.
On a power drawing, keep this function reference connected to the selected equipment and its complete designation. A multifunction relay can implement several numbered functions. This entry explains the reference; it supplies no settings or commissioning procedure.
How to read it
- Identify whether the device uses measured temperature, electrical inputs or another documented implementation.
- Link the function to the protected equipment and manufacturer documentation.
Information to show or reference
- Identify the protected equipment.
- Reference required measurements or sensors.
- Link the thermal function documentation.
A distinction that matters
A thermal relay, temperature sensor and instantaneous overcurrent element are different devices or functions.
Sources you can follow
These public references support the explanation and provide further detail. Their graphics and downloadable files remain with their publishers.
Public reference table of ANSI device-function numbers
Public manufacturer table used to check the base function-number name.
IEEE C37.2-2022: power-system device function numbers
Normative publication reference for the device-function convention.
Relion 620: functions, codes and symbols
Public examples of manufacturer-specific function names and suffixes.
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.