M
Three-phase motor
An electrical motor load connected to its switching and protective equipment.
SLD / Schematic
Protection functions · 56
Field application relay
Initiates application of excitation at the appropriate step of a machine starting sequence.
SLD / Schematic · 56
What it represents
Initiates application of excitation at the appropriate step of a machine starting sequence.
In a drafting package, connect this reference to the speed/sequence permission and excitation supply. The associated drawing should trace the field application command and field switching device; the number identifies the role and does not specify the terminal arrangement, ratings or operating settings.
This designation is useful when reading machine and legacy control drawings. Retain the documented function on an existing drawing and consult the original equipment manual before assigning it to a new design.
How to read it
- Identify the speed/sequence permission and excitation supply.
- Trace the field application command and field switching device.
Information to show or reference
- Label the speed/sequence permission and excitation supply.
- Cross-reference the field application command and field switching device.
- Identify the device tag, manual revision and logic drawing that define this implementation.
A distinction that matters
Field application is a sequence action; loss-of-excitation 40 supervises abnormal excitation after or during operation.
Sources you can follow
These public references support the explanation and provide further detail. Their graphics and downloadable files remain with their publishers.
ANSI device-number and suffix reference table
Public manufacturer number/name association. Drafting explanations are independently written.
IEEE C37.2-2022: power-system device function numbers
Normative device-number publication; exact edition wording and compliance require the licensed standard.
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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