CERN chooses ARC Informatique’s PcVue supervision software package to manage LHC ventilation and cooling

The LHC (Large Hadron Collider) is the most powerful particle accelerator ever built to date. Inaugurated in October 2008 at CERN, near Geneva, on the Franco-Swiss border, it is housed in a circular tunnel with a circumference of 27 kilometres buried at an average depth of 100 metres, on the site that formerly housed the LEP (Large Electron Positron) collider, which it is replacing. Unlike the LEP in which the electrons and positrons were accelerated to produce collisions, the LHC accelerates protons from the hadron family, and heavy ions such as lead. This monumental apparatus allows physicists from the world over to study the smallest known particles with a view to revealing the secrets of our universe.

To achieve this, two beams of hadrons or heavy ions circulating in opposite directions are accelerated in a 27-kilometre ring to reach a speed close to the speed of light at very high energy levels. When these particles enter into head-on collision, the shock generated makes it possible, for example, experimentally to reproduce conditions close to those that occurred just after the Big Bang. The particles created by these collisions are analysed by means of special detectors delivering data that are interpreted by researchers from over one hundred countries.

To make it possible to perform these experiments, the LHC requires no less than 9,300 magnets cooled to -271.3°C (1.9K) thanks to 10,080 tonnes of liquid nitrogen and 130 tonnes of liquid helium, via a gigantic cryogenic distribution system. Such an installation also requires a ventilation system sized to establish an atmosphere suited both to the people working in it and to the equipment installed in the experimental zones. The LHC’s ventilation also provides the cold smoke extraction and the pressurisation functions in the underground survival zones. The design of the ventilation system incorporates modifications to the existing ventilation process (renovation of the LEP ventilation) along with new equipment.

To allow it to manage the LHC’s ventilation and cooling systems, CERN needed a supervision software package suited to the size of this application, which houses more than 200 pieces of automated equipment, at an attractive price and above all offering a competitive Total Cost of Ownership. The solution proposed also had to meet CERN’s integration requirements: network constraints of course, and also availability constraints. “In the architecture adopted by CERN, the number of clients able to connect up simultaneously to the system is close to 30 (8 fat clients, 20 Terminal Server clients), which means it must operate virtually in real-time. The availability constraint is therefore extremely high. Consequently, the system must always be accessible. We have therefore applied the principle of redundancy enabling a server to take over if another server is no longer available,” explains Lionel Diers, Project Leader at Assystem France, the service provider in charge of the project.

After having studied the supervision solutions available on the market, in order to meet these specifications CERN settled on the PcVue package developed by the company ARC Informatique. ”Besides the fact that the PcVue solution meets our performance and price requirements, this product also has the advantage of being well known to system integrators who have a great deal of experience with its implementation,” declares Mario Batz, Project Leader in the CERN Engineering Department’s cooling and ventilation group. PcVue makes it possible to connect up to automation equipment by means of standard field networks such as Profibus, Industrial Ethernet and many others in order to monitor and/or control the process being supervised. The supervisor’s task consists of collecting data, and sending them to an Information System where they are analysed. These data are processed directly by PcVue so they can be displayed in animated views (called mimic displays) by means of symbols that can be instantiated (called objects). The information collected is translated into standard PcVue objects (event objects and alarm objects for the “On/Off” data, analysis of the graphs for the analogue data) and then archived in databases with a view to analysing them at a later time in ancillary, spreadsheet type tools, etc. In this case, PcVue manages 80,000 variables (66,000 of which are archived), 1,200 mimic displays and 600 objects.

PcVue provides major innovations with a view to reducing further the deployment and operating times and costs of industrial process supervision projects, particularly in large-scale applications such as assembly factories, nuclear power stations, chemical, pharmaceuticals or food-processing plants, etc. “The specific feature of PcVue with respect to the other tools available on the market is the notion of tree structure. Here it is a question of facilitating the instantiation of objects, and therefore of limiting the development work. So, for several items of “variable speed drive” type equipment, for example, you just have to create a “variable speed drive” object and instantiate it each time that piece of equipment exists in the process,” explains Lionel Diers from Assystem France.

There are also other particularly interesting tools in the PcVue software such as HDS (Historical Data Server) archiving, which manages the interface between the supervision system and the archives database, or “Terminal Server” which, thanks to a Windows function, makes it possible to use several PcVue sessions on any given station. In an environment such as the LHC’s, this function is particularly attractive in terms of utilisation and deployment flexibility because the site is vast and there are a large number of “clients” (users connecting up to the application).

Still with a view to facilitating deployment and reducing the operating costs of process supervision systems, PcVue also supports the Vmware virtual environment which makes it possible to run several operating systems separately from each other on a single machine as if they were running on distinct physical machines. This virtualisation process thus makes it possible to replace several real machines distributed around the site to be supervised, which are generally underused and quickly become obsolete compared with a single PC that simulates as many virtual machines as required by allocating part of its resources to each one of them. An additional virtual supervision station can be added simply by copying/pasting an existing virtual machine on the central PC and providing the user with a terminal. In the case where the process is modified (change of rate, new needs, etc.), you just have to adjust the resources allocated by the central PC to the virtual machine concerned by this change. “Given the scale of the LHC’s application, the implementation of a virtual infrastructure has led to a drastic reduction in the number of physical machines used with, as a bonus, lower power consumption, great ease-of-use and excellent integration in CERN’s IT architecture,” points out Lionel Diers from Assystem France.

This means that supervision of the LHC ventilation only requires two physical machines, each with 12 Gb RAM and six 250 Gb hard drives. The supervision workloads are shared between these two redundant physical servers (Windows 2003 servers), with the first one ensuring the functions of the PcVue acquisition server No. 1, Web server (users via the Internet) and database server (for the archiving of data), and the second one fulfilling the functions of PcVue acquisition server No. 2 and Terminal Server.

The on-site acquisition stations – eight in all (one per experimental area) – are touch-screen server stations intended to be used by the local maintenance operators. As the intervention areas are approximately 2 km apart these stations are essential and also make it possible to take control of the ventilation installations should one of the two central servers encounter a problem.

This is not the first time ARC Informatique, Assystem France and CERN have cooperated on a project. The three have already worked together on two other projects: CSAM (CERN Safety Alarm Management) for the supervision of CERN’s technical alarms, fire detectors and gas detectors, and RAMSES (Radiation and Monitoring System for the Environment and Safety) for putting into service and maintaining an ionising radiation control system in CERN’s experimental facilities. “The strong points in the ARC Informatique/Assystem France offer lie above all in the complementarity of their teams, the responsiveness of the service and competence of the technical support they provide, and the fact that they focus on the users’ needs,” explains CERN’s Mario Batz. To develop and continue to improve PcVue, the ARC Informatique teams rely on the experience they have accumulated thanks to a total of more than 38,000 licences installed.

Caption CERN-LHC-N°1.jpg : Buried at an average depth of 100 metres, the LHC tunnel has a circumference of nearly 27 kilometres.
Caption CERN-LHC-N°2.jpg : One of the LHC’s ventilation units.
Caption CERN-LHC-N°3.jpg : PcVue representation of an experimental zone and of its ventilation units.