Functional block · DVFS

Duty-standby ventilation fan selection

Functional block · Switchrooms

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

Assigns the available room ventilation fans to the documented duty and standby roles.

A simple example

In a switchroom containing transformers and auxiliary panels, the room controller can supervise fan availability and send an alarm when the documented ventilation duty is not achieved. For this reference, the drawing identifies “Fan availability” at the input and “Duty-fan selection” at the output. A standby fan does not prove adequate airflow.

Fan availabilityDVFSDuty-fan selection
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: Fan availability. Identify its source device or document and the state represented on the drawing. Follow the named output: Duty-fan selection. Cross-reference its destination and separate the command from confirmation that the equipment responded.

Input
Fan availability
Output
Duty-fan selection
Application reference
An explanation of a named drawing function or circuit relationship; the project documents define the equipment and its connections.

Read the source: Ventilation in MV substations

Schematic · DVFSDuty-standby ventilation fan selection: original educational illustration
Original educational illustrationSee source and graphic notes

What it represents

Assigns the available room ventilation fans to the documented duty and standby roles. Ventilation control coordinates the equipment that manages heat and air movement in an electrical room. A temperature request, a fan command and proof of airflow are separate signals, and the room design determines how they interact.

In a switchroom containing transformers and auxiliary panels, the room controller can supervise fan availability and send an alarm when the documented ventilation duty is not achieved. For this reference, the drawing identifies “Fan availability” at the input and “Duty-fan selection” at the output. A standby fan does not prove adequate airflow.

Identify the monitored space, the selected ventilation mode and the equipment feedback. Avoid inferring airflow, temperature limits or a fire response from a generic fan symbol; these require the room-services design. 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: Fan availability. Identify its source device or document and the state represented on the drawing.
  • Follow the named output: Duty-fan selection. Cross-reference its destination and separate the command from confirmation that the equipment responded.
  • A standby fan does not prove adequate airflow.
  • Identify the monitored space, the selected ventilation mode and the equipment feedback. Avoid inferring airflow, temperature limits or a fire response from a generic fan symbol; these require the room-services design.

Information to show or reference

  • Label the source and connection reference for fan availability.
  • Identify the destination and defined state of duty-fan selection.
  • Record the equipment or control-document revision supporting this functional block.
  • Check this application limit in the project design: A standby fan does not prove adequate airflow.

A distinction that matters

A standby fan does not prove adequate airflow. 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.

Ventilation in MV substations

Public technical context for switchroom ventilation interfaces. Heat removal, condensation and environmental design context. The application text and educational graphic are independently authored; the publisher does not certify this representation.

Schneider Electric · Public reference checked 3 November 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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