# Hydrogen electrolyser

Canonical URL: https://eloragrid.ai/symbols/hydrogen-electrolyser
Publisher: Elora Grid
Updated: 2026-10-28
Lookup label: ELY
Drawing use: SLD
Reference families: IEC, IEEE / ANSI

A DC load that splits water into hydrogen and oxygen, supplied through a rectifier as a controllable sink in a microgrid.

## In plain English

### What does Hydrogen electrolyser mean?

An electrolyser uses DC current to split water into hydrogen and oxygen. In microgrids and renewable hubs it acts as a large controllable load that can absorb surplus solar or wind generation, with the hydrogen stored for later use in a fuel cell or sold off site.

### A simple example

On a single-line diagram the electrolyser stack appears as a DC load fed from a transformer-rectifier or an active front-end rectifier. Large units show the rectifier transformer, harmonic filtering and a DC busbar to the stack; smaller units may be drawn as a single block labelled with the stack rating.

### What the drawings help you do

Thyristor rectifiers for large electrolysers draw significant harmonic current and reactive power, so filters or compensators may be needed. The symbol does not state ramp rate, minimum load or the gas plant constraints that limit how flexibly the electrolyser can follow generation.

### This particular reference

A DC load that splits water into hydrogen and oxygen, supplied through a rectifier as a controllable sink in a microgrid. An electrolyser consumes electricity to make hydrogen; a fuel cell consumes hydrogen to make electricity.

### Terms

- DC: Direct current: electricity flowing in one direction.
- Winding: A coil of conductor inside an electrical machine or transformer.
- Rating: A value stating the conditions for which equipment is specified.

Concept diagram: Identify the device and form → Read the connections and state → Check the equipment reference
A guide to reading this reference. The original symbol illustration and its drawing notes appear below; these boxes are not a wiring diagram.

- [IEC graphical symbols for diagrams](https://tc3.iec.ch/tc-activity/graphical-symbols-for-diagrams/)
- [Battery energy storage and power conversion](https://www.eaton.com/sg/en-us/products/energy-storage.html)


## What it represents

An electrolyser uses DC current to split water into hydrogen and oxygen. In microgrids and renewable hubs it acts as a large controllable load that can absorb surplus solar or wind generation, with the hydrogen stored for later use in a fuel cell or sold off site.
On a single-line diagram the electrolyser stack appears as a DC load fed from a transformer-rectifier or an active front-end rectifier. Large units show the rectifier transformer, harmonic filtering and a DC busbar to the stack; smaller units may be drawn as a single block labelled with the stack rating.
Thyristor rectifiers for large electrolysers draw significant harmonic current and reactive power, so filters or compensators may be needed. The symbol does not state ramp rate, minimum load or the gas plant constraints that limit how flexibly the electrolyser can follow generation.

## How to read it

- Read the rectifier type to judge harmonic and reactive impact.
- Treat the stack as DC load; its rating is often given in MW of DC input.

## Information to show or reference

- State stack DC rating and ramp limits.
- Show rectifier, transformer and filters.
- Reference minimum load and process interlocks.

## Important distinction

An electrolyser consumes electricity to make hydrogen; a fuel cell consumes hydrogen to make electricity.

## Facts

- Electrical role: Controllable DC load
- Supply: Rectifier from AC network
- Power quality: Rectifier harmonics may need filtering
- Preview: Independent educational illustration; consult the applicable standard and project legend for the exact graphic

## Public references

- [IEC graphical symbols for diagrams](https://tc3.iec.ch/tc-activity/graphical-symbols-for-diagrams/) — IEC. IEC graphical symbol context for loads and conversion elements.
- [Battery energy storage and power conversion](https://www.eaton.com/sg/en-us/products/energy-storage.html) — Eaton. Public power conversion context for storage-type systems.

## 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.