---
title: How to stop one hydrogen generator in a parallel system
description: How to stop a single LNI Swissgas H2 generator running in a parallel system for maintenance or servicing.
---

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June 11, 2025

# How to stop one hydrogen generator in a parallel system

## When HG models (HG BASIC, HG PRO and HG PRO M) work in parallel mode, shutting one unit down for maintenance, etc. requires you to follow specific steps to avoid shutting off the whole system.

Where two (or more) H2 generators are connected in parallel, pressing "STOP" or "CLOSE" on one generator will apply the same action to all connected generators. For maintenance, service, etc. of only one generator, this is not favourable, so it is recommended to follow these steps to isolate the unit for maintenance:

1. Go to: Menu → Setup → Parameter → Parallel Mode
2. Set the generator you want to stop to **"Local"**
3. The other generators will continue running normally
4. The generator you wish to stop can now be put in STOP mode
5. Once the maintenance is complete, go back to the same menu and set the generator back to **"Remote"** – it will resume operation automatically

If the generator needs to be powered off for the servicing, it will result in the parallel system going into pre-alarm, as it cannot detect the generator. In this scenario, the other generator(s) should operate normally despite the pre-alarm.

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