# Switchroom enclosure heater-failure alarm

Canonical URL: https://eloragrid.ai/symbols/switchroom-enclosure-heater-failure-alarm
Publisher: Elora Grid
Updated: 2026-11-03
Lookup label: SEHA
Drawing use: Schematic
Reference families: Manufacturer

Representation: Functional block
Installation focus: switchrooms
Input: Heater command and feedback
Output: Heater fault indication

Reports the defined failure condition of an enclosure conditioning-heater circuit.

## In plain English

### What this block does

Reports the defined failure condition of an enclosure conditioning-heater circuit.

### A simple example

In a switchroom, water ingress, temperature, humidity and equipment-service alarms can be sent to the station controller with separate point names so an operator can identify the affected area. For this reference, the drawing identifies “Heater command and feedback” at the input and “Heater fault indication” at the output. Heating effectiveness needs more than command status.

### What the drawings help you do

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

### Terms

- Input: Heater command and feedback
- Output: Heater fault indication
- Application reference: An explanation of a named drawing function or circuit relationship; the project documents define the equipment and its connections.

Concept diagram: Heater command and feedback → SEHA → Heater fault indication
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

Reports the defined failure condition of an enclosure conditioning-heater circuit. Environmental supervision turns measurements or contact states into clearly named room-service indications. A sensor measures a condition; the supervisory function decides whether the assigned alarm or control response is needed.
In a switchroom, water ingress, temperature, humidity and equipment-service alarms can be sent to the station controller with separate point names so an operator can identify the affected area. For this reference, the drawing identifies “Heater command and feedback” at the input and “Heater fault indication” at the output. Heating effectiveness needs more than command status.
Keep sensor location, alarm thresholds, delay and monitoring coverage in the room-services schedule. An environmental alarm is a diagnostic input, not a complete assessment of electrical equipment condition. 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: Heater command and feedback. Identify its source device or document and the state represented on the drawing.
- Follow the named output: Heater fault indication. Cross-reference its destination and separate the command from confirmation that the equipment responded.
- Heating effectiveness needs more than command status.
- Keep sensor location, alarm thresholds, delay and monitoring coverage in the room-services schedule. An environmental alarm is a diagnostic input, not a complete assessment of electrical equipment condition.

## Information to show or reference

- Label the source and connection reference for heater command and feedback.
- Identify the destination and defined state of heater fault indication.
- Record the equipment or control-document revision supporting this functional block.
- Check this application limit in the project design: Heating effectiveness needs more than command status.

## Important distinction

Heating effectiveness needs more than command status. 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: Heater command and feedback
- Output / connection: Heater fault indication
- Lookup label: SEHA 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 environmental supervision. 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.