# Software, Control, Safety and Certification

# What are the safety interlocks build-in? e.g. in case of hydrogen leak? Or drop of pressure?

The Electrolyzer has various sensors to ensure safe operation at all times. If a leak is detected or the pressure unexpectedly falls, the Electrolyzer will shut itself down and send alarm or error messages via the Enapter monitoring system.

# What safety features are integrated?

The Electrolyzer is designed to be intrinsically safe. It self-pressurizes the hydrogen side and performs leak test routines at regular intervals or when some data suggests a leak could be present. The EL2.1 is CE certified, and in our experience, it is very straightforward for our customers to integrate the Electrolyzer into the safety concept on their sites. Depending on the specific site safety concept and local regulations, some of our customers install additional safety devices such as a hydrogen sensor in order to cut the power if any hydrogen leaks occur on the site. The Electrolyzer also has a dry contact on the front panel that triggers a safe shutdown based on an external signal.

# Are Dryers connected to the EMS system? Can the Dryer be controlled via Modbus?

While we believe our EMS is the best way to access, monitor and control the Electrolyzers and Dryers, it is not necessary to use it as the main system controller. To control the Electrolyzer our customers can use the Ethernet port with Modbus TCP to integrate it with their system of choice. At the moment, this is only available for the Electrolysers. Unfortunately, the same type of communication is not currently available for our Dryers 2.0 and 2.1. However, we are looking into the matter and in the future this type of connection may become available. At this moment, our software and testing teams are working on a solution for making the dryers truly act as a passive device, so that only modbus communication to the EL is necessary to run the system in a robust and smart way.

However, we highly recommend using the EMS or at least connecting the devices to the cloud using an Enapter gateway. This extend the warranty of the devices and allows the user to integrate, monitor and control complex energy systems, via rule based control.

The adaptability of the EMS allows it to communicate and read data from every standard of communication normally used in micro-grid systems, as well as analogue inputs. If you would like to integrate a new system (inverters/power meters/fuel cells) into the EMS ecosystem, please contact us for help!

# Has the water inlet some sort of monitoring?

The water treatment has no monitoring installed - depending on the use of the system, suitable maintenance intervals should be defined to prevent the filters from becoming dirty and the water quality from falling. We are planning to integrate a conductivity / TDS1 sensor into the EMS adapter via UCM. If you were able to install such a sensor in your water pipe to the Electrolyzer, the risk of damage due to poor water quality would be significantly reduced.

The Conductivity Measurement Module is used to receive data from Enapter conductivity sensor (ENP-SENSE-TDS) with a 0…10 V signal and temperature sensor. The Conductivity Measurement Module sends the collected data to the Enapter Gateway and Cloud via secure wireless connection.

Enapter ENP-CS Module is based on Enapter ENP-AI4-50V Module.

A water pressure sensor at the inlet of the electrolyser was integrated. In order to supply the EL2.1 with clean DI water for refilling. Water must be present in the electrolyser water refilling pipe at a pressure between 0.5 bar and 4 bar. If the EL 2.1 does not detect the water’s presence, the system will not refill and will stop operation while it waits for water input pressure to appear. The data collected from the sensor are displayed in our EMS system for better management and monitoring of the water inlet pressure.

The Electrolyzers have an internal hydrogen leakage detection, so they will shut themselves down in case of a substantial leak being detected. However, there is no gas sensor present in each machine. If required by the safety concept on the end user site, we recommend a sensor to be installed at the top of the cabinet. We recommend defining two safety levels (for example at 10% and 25% of LEL2):

  1. When a small unexpected leak occurs, a dry contact on the front panel of the EL2.1 triggers a safe shutdown.

  2. In critical situations with large leakages, simply cut off the power.

# Are the modules equipped with an internal ventilation system? Is the internal ventilation enough to dilute any hydrogen leakage and to reduce its concentration below LEL[^2]? In case the internal ventilation stops, also hydrogen production is automatically discontinued?

Yes, the Electrolyzers have an internal ventilation system that dilutes any leakage (only in case of damage, normally the Electrolyzer has zero external leakages) below hydrogen LEL. In case the internal ventilation stops, the hydrogen production also stops.

# In case of an emergency/failure, how much hydrogen can get out of the cabinet? Potential hydrogen leakages will be diluted thanks to the ventilation in any case, or there is any possibility for pure hydrogen to get out of the cabinet?

Each Electrolyzer contains a maximum of around 18 NL of hydrogen gas. If it escapes due to a sudden internal leakage of the hydrogen piping, it would be diluted by the ventilation system.

# Do I have to use the Enapter EMS monitoring system or can the system also be controlled via the Ethernet port via Modbus?

While we believe our EMS is the best way to access, monitor and control the Electrolyzers, but you don’t have to use it. To control the Electrolyzer our customers can use the Ethernet port with Modbus TCP to integrate it with their system of choice.

# Is it possible to remotely control the system in terms of on/off switching, hydrogen pressure, flow regulation, etc?

Absolutely, the best way to control our Electrolyzers is via our Enapter energy management system, which allows full monitoring and control via a web dashboard and mobile app. It also collects monitoring data to enable efficient support and service of the system.

# What does the monitoring measure and control when it comes to the Dryer?

As for our software monitoring system, it measures and displays input pressure, output pressure, several temperature levels, fan speeds, digital in- and outputs. You can control (start/stop/reboot/OTA3 firmware update). This is for the Dryer only, for the Electrolyzer there is obviously much more specs to monitor and control. Please contact us for a demo of the monitoring software.

# What kind of control system is used in the Electrolyzer? We require PLC control. If it is PLC control, which brand of PLC will be suitable for the equipment?

Our Electrolyzers are monitored and controlled by the Enapter EMS. It is a software-based system, where all the data from the Enapter Electrolyzers is collected by a local “gateway”, which is a Linux based PC, such as Intel NUC. We can provide a suitable interface to connect the Gateway to your PLC, such as Modbus or Ethernet. It is also possible to control each individual Electrolyzer via a Modbus communication interface.

# What kind of smart production regulation possibilities are there using the EMS in my system?

The EMS and its system of extension modules can perform a large variety of smart features. Due to the rule based control, the system can truly be programmed to be as versatile as needed.

For example the system can regulate production rates to keep the output pressure stable at a certain pressure set point (useful for constant flow rate requirements). Another example is the use case for the Big Thing micro-grid, using the EMS and the integrated extension modules, the system can regulate which devices are running when, anticipate bad weather and determine how much hydrogen is needed to be stored for continuous autonomy.

# Apart from the system components used in the Big Thing, can we use the EMS extensions to integrate inverters/power meters/fuel cells from other suppliers?

Short answer: Yes! The adaptability of the EMS allows it to communicate and read data from every standard of communication normally used in micro-grid systems, as well as analogue inputs. If you would like to integrate a new system into the EMS ecosystem, please contact us for help!

# What does the Enapter mobile app enables me to do?

Enapter's Mobile application is an interface to system integrators and end-users’ connected devices such as Electrolyzer, Dryer, Communication Module and Extensions. The Enapter mobile app allows easy and secure system setup using QR codes, management and monitoring all over the world. Mobile applications are available for Android and iOS.

# Which operating systems are supported by Enapter EMS system?

The mobile app is available for Android and iOS. The web dashboard runs in any standard Internet browser, such as Google Chrome, Firefox, etc.

# Where I can download the Application?

You can download it in the Apple app store or Google Play app store.

# How can I setup custom control logic for my energy system?

The Enapter Gateway enables this functionality. One Gateway can be installed per user site to enable advanced control features and mitigate Internet connectivity issues. Using the Gateway, the Enapter Engine can be configured in a simple if-then-else logic defined by the user. This logic allows to send action commands to devices based on conditions driven by sensors or other device’s data integrated in the energy system. The logic is set using the convenient CLI4 and can extend to any level of branching and complexity. In cases when standard condition rules are not sufficient it is possible to extend functionality by contributing additional logic using "Lua" scripting language.

# How can I export data for analysis?

The Enapter Cloud collects performance and error data from the Enapter Gateway and all connected devices such as Electrolyzers, Dryers and UCM. It stores it in a time series database and provides real-time or on-demand visualization of collected data on customizable dashboards. Specific data sets can also be downloaded in CSV format with a few clicks on Exports page.

# In the event of an emergency, can the system be switched off by cutting off the electrical power in order to stop hydrogen production immediately? Once the emergency has been cleared, how long does it take to switch the Electrolyzer on again?

Yes, of course. If you have for example an external hydrogen sensor, you could trigger a relay and cut of the power to the system. Once the emergency is cleared, the Electrolyzer could be restarted with the normal procedure, the time depends on the ambient conditions but if the temperature is >20 °C should be no more than 4-5 minutes to reach maximum production rate (otherwise, a heating period will first be initialized to heat up the system up to the minimum temperature).

The EL2.1 has a dry contact on the front panel, which can be used to create a safety-chain. If the contact is closed, the Electrolyzer will immediately initiate an emergency shutdown.

# Is your system CE certified?

The EL2.1 is CE certified.

# Is the Electrolyzer ATEX2 certified and, if so, for which zone - 0, 1 or 2?

No, our system is not designed to be installed in an ATEX area. During normal operation, there is no leakage of any hydrogen or oxygen gases from the system. The product gases are only released from the designated interfaces (H2 outlet, O2 vent, and H2 purge) that have to be correctly managed during the on-site installation. It is the project developers/installers responsibility to ensure that the area where the electrolyzers are installed must never contain any explosive atmospheres during any time of regular operation. An appropriate safety concept must be in place to mitigate the risks of any failures that could result in leakage of flammable gases. Such a safety concept could involve, for example, hydrogen sensors, forced ventilation, or natural ventilation.

# Is the pipeline in accordance with any certification?

We make all our hydrogen piping in accordance with ASME B31.12 for hydrogen piping and pipelines. All the European guidelines refer to the ASME, which is something like a “gold standard” for anyone working with hydrogen.

# Can the system itself introduce in the lab an ATEX area surrounding the Electrolyzer (implying specific requisites for other equipment installed)? Is it necessary to have the H2 outlet with a weldable connection, as to avoid the formation of a potentially dangerous (ATEX) zone in the area surrounding the system?

The Electrolyzer normally has a standard ¼” Swagelok bite-type Stainless Steel connector for the hydrogen outlet piping. The outlet pipe is protected internally by relief and check valves from any gas flow backwards into the machine from the external tank/H2 distribution lines. We don’t believe it is necessary to weld the connection to avoid ATEX – it is quite typical to have these Swagelok connections in gas piping in laboratories. However, this may change with local rules and regulations.

The only thing to note in terms of safety areas is that the Electrolyzer system has two outlets that need to be connected to a safe area without any ignition sources. The first is the oxygen vent, which consists of 250NL/hr of oxygen gas at atmospheric pressure and may also contain some water and a very small percentage of hydrogen. The other is the hydrogen purge pipe, from which the Electrolyzer releases the pressurized hydrogen gas after a system shutdown – here, it releases about 10NL of hydrogen gas at 35 bar into the atmosphere within about 2 seconds.

# Can the EL2.1 be managed without the Enapter Mobile Application or Cloud?

The most convenient and simple way to manage and monitor the EL 2.1 is via the Enapter Mobile App.

At the same time, the Modbus TCP interface can be used to provide all required data and functionality for integration with third party management software and Enapter provides full Modbus register table (here for the EL 2.1) together with samples of management scripts in python. The scripts are hosted on our github page and they help to understand the flows of monitoring, control and commissioning of the device.

1: Total Dissolved Solids

2: Low Explosive Limit

3: Over the air

4: Command line interface