# Switchroom HVAC common-fault interface

Canonical URL: https://eloragrid.ai/symbols/switchroom-hvac-common-fault-interface
Publisher: Elora Grid
Updated: 2026-11-03
Lookup label: SHCI
Drawing use: Schematic
Reference families: Manufacturer

Representation: Functional block
Installation focus: switchrooms
Input: HVAC fault contact
Output: Station HVAC alarm

Carries the HVAC unit's declared fault output into the electrical station alarm system.

## In plain English

### What this block does

Carries the HVAC unit's declared fault output into the electrical station alarm system.

### 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 “HVAC fault contact” at the input and “Station HVAC alarm” at the output. The contact does not identify every HVAC failure.

### What the drawings help you do

Start at the named input: HVAC fault contact. Identify its source device or document and the state represented on the drawing. Follow the named output: Station HVAC alarm. Cross-reference its destination and separate the command from confirmation that the equipment responded.

### Terms

- Input: HVAC fault contact
- Output: Station HVAC alarm
- Application reference: An explanation of a named drawing function or circuit relationship; the project documents define the equipment and its connections.

Concept diagram: HVAC fault contact → SHCI → Station HVAC alarm
A reading guide. The entry's original illustration and input/output facts describe this application.

- [Ventilation in MV substations](https://www.electrical-installation.org/enwiki/Ventilation_in_MV_Substations)


## What it represents

Carries the HVAC unit's declared fault output into the electrical station alarm system. 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 “HVAC fault contact” at the input and “Station HVAC alarm” at the output. The contact does not identify every HVAC failure.
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: HVAC fault contact. Identify its source device or document and the state represented on the drawing.
- Follow the named output: Station HVAC alarm. Cross-reference its destination and separate the command from confirmation that the equipment responded.
- The contact does not identify every HVAC failure.
- 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 hvac fault contact.
- Identify the destination and defined state of station hvac alarm.
- Record the equipment or control-document revision supporting this functional block.
- Check this application limit in the project design: The contact does not identify every HVAC failure.

## Important distinction

The contact does not identify every HVAC failure. 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.

## Facts

- Representation: Functional block
- Installation focus: Switchrooms
- Input / boundary: HVAC fault contact
- Output / connection: Station HVAC alarm
- Lookup label: SHCI is a library lookup label, not a standard device designation.

## Public references

- [Ventilation in MV substations](https://www.electrical-installation.org/enwiki/Ventilation_in_MV_Substations) — Schneider Electric. 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.

## Graphic scope

Independent original educational concept illustration by Elora Grid. Not a certified standards graphic or manufacturer footprint. Unitless; not to scale. Original artwork licence: https://creativecommons.org/licenses/by/4.0/. Publisher material is linked only.