Functional block · TNCR

Transformer neutral-earthing conductor reference

Functional block · Switchyards

An independently authored application reference. The drawing shows the named function or circuit relationship; use the project legend and selected equipment documentation for its drafting form and connections.

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In plain English

What this block does

Identifies the conductor connecting the assigned transformer neutral to its specified earthing equipment.

A simple example

In a switchyard arrangement, the earthing references help connect each primary equipment structure and surge-protection device to the correct earth-grid interface. Separate details show actual joints, sizes and installation routes. For this reference, the drawing identifies “Transformer neutral” at the input and “Neutral-earthing equipment” at the output. Its duty differs from a tank protective bond.

Transformer neutralTNCRNeutral-earthing equipment
A reading guide. The entry's original illustration and input/output facts describe this application.

What the drawings help you do

Start at the named input: Transformer neutral. Identify its source device or document and the state represented on the drawing. Follow the named output: Neutral-earthing equipment. Cross-reference its destination and separate the command from confirmation that the equipment responded.

Input
Transformer neutral
Output
Neutral-earthing equipment
Application reference
An explanation of a named drawing function or circuit relationship; the project documents define the equipment and its connections.

Read the source: Earthing connections

Schematic · TNCRTransformer neutral-earthing conductor reference: original educational illustration
Original educational illustrationSee source and graphic notes

What it represents

Identifies the conductor connecting the assigned transformer neutral to its specified earthing equipment. Earthing and lightning interfaces identify the connections between equipment metalwork, primary protection devices and the station earthing network. Their electrical purpose differs from their physical conductor route or electrode geometry.

In a switchyard arrangement, the earthing references help connect each primary equipment structure and surge-protection device to the correct earth-grid interface. Separate details show actual joints, sizes and installation routes. For this reference, the drawing identifies “Transformer neutral” at the input and “Neutral-earthing equipment” at the output. Its duty differs from a tank protective bond.

Name every connected item and the earthing design reference. The illustrative connection does not establish touch or step voltages, conductor sizing, lightning coverage or safe working conditions. The functional block is an independent explanation of this named application. Equipment-specific ratings, terminal connections and operating conditions must be established in the project documentation.

How to read it

  • Start at the named input: Transformer neutral. Identify its source device or document and the state represented on the drawing.
  • Follow the named output: Neutral-earthing equipment. Cross-reference its destination and separate the command from confirmation that the equipment responded.
  • Its duty differs from a tank protective bond.
  • Name every connected item and the earthing design reference. The illustrative connection does not establish touch or step voltages, conductor sizing, lightning coverage or safe working conditions.

Information to show or reference

  • Label the source and connection reference for transformer neutral.
  • Identify the destination and defined state of neutral-earthing equipment.
  • Record the equipment or control-document revision supporting this functional block.
  • Check this application limit in the project design: Its duty differs from a tank protective bond.

A distinction that matters

Its duty differs from a tank protective bond. This reference describes the named application; it does not establish a new IEC graphical symbol, an ANSI device-function number or an exact manufacturer connection diagram.

Sources you can follow

These public references support the explanation and provide further detail. Their graphics and downloadable files remain with their publishers.

Earthing connections

Public technical context for switchyard earthing and lightning interfaces. Protective earthing, bonding and earth-electrode interfaces. The application text and educational graphic are independently authored; the publisher does not certify this representation.

Schneider Electric, Electrical Installation Guide · Public reference checked 28 October 2026 · Link only

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. Original artwork is available under CC BY 4.0. Third-party references retain their own terms.

Entry JSON · Entry Markdown · Last editorial update: 3 November 2026

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