CERN, the European Organization for Nuclear Research, is one of the largest scientific research centers in the world. The particle accelerator and detector instruments used in its laboratory study the physics of the universe in order to understand its makeup. Its immense Large Hadron Collider (LHC) project, located in Geneva near the Franco-Swiss border, commenced in the fall of 2008 and is the world's largest and highest-energy particle accelerator, with a circumference of 17 miles (27 kilometers).
The objective of the LHC is to uncover some of the most fundamental questions of physics. The LHC accelerates protons from the hadron family, allowing physicists to study some of the smallest known particles. To accomplish this, two beams of hadrons or heavy ions circulating in opposite directions are accelerated in a 27-kilometer 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 analyzed by means of special detectors delivering data that are interpreted by researchers from over one hundred countries. This is why the monitoring and tracking of the various components of the LHC is so critical. Experiments are closely monitored to ensure every process is optimized, and every piece of equipment is achieving peak performance.
In order to perform these complex, large-scale experiments, the LHC requires a minimum of 9300 magnets cooled to -458 °F (-271.3 °C) by 10,080 tons of liquid nitrogen and 60 tons of liquid helium delivered via a huge cryogenic distribution system. This installation also requires a ventilation system sized to establish an atmosphere suited to both personnel and the equipment located in the experimental zones. In addition, the LHC's ventilation provides the cold smoke extraction and pressurization functions in the underground survival zones.
To facilitate and manage their ventilation and cooling facilities, CERN required a control and supervisory software package that would suit the enormous size of this application, which houses over 200 pieces of automation equipment, while maintaining a competitive cost, including a reasonable total cost of ownership.
In the architecture adopted by CERN, the number of clients able to connect to the system is 28 (eight fat clients and 20 terminal server clients), which means that it must operate virtually in real time. With an extremely high availability constraint, redundancy was applied to enable one server to take over if another is no longer available.
CERN chose the PcVue (www.pcvuesolutions.com) SCADA supervision software developed by ARC Informatique (www.actors-solutions.net/ARC-INFORMATIQUE) and installed on-site by Assystem France (www.assystem.com/fr/accueil.html) to monitor and control its ventilation systems and the 200 associated programmable controllers. "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," states Mario Batz, project leader in the CERN Engineering Department's cooling and ventilation group.
The PcVue SCADA system monitors some 80,000 I/O points for the LHC's cooling and ventilation application. It monitors everything from pressure to temperature to water levels in order to provide a secure, safe and comfortable environment for the workers in the facility.
Siemens provides all of the PLCs being used in the LHC's network. It has mainly used its S7-200 and S7-300 models, selected for their real-time performance and universal design. PcVue is connecting to the PLCs via Industrial Ethernet and Profibus through an OPC server connection.
Initially the supervisor performs data acquisition activities and the collected data is then sent to the Information System for further analysis. Operators and management use PcVue SCADA not only to conduct supervision, but also to operate, view, act on and diagnose the control process. It provides a global overview of the data.
PcVue collects and processes data, displaying certain assigned data points in PcVue SCADA's animated displays, otherwise known as mimics. PcVue SCADA uses object-oriented technology that allows the developer to assign specific data points to objects and save them to a library for reuse. CERN found PcVue's graphical user interface extremely user-friendly when developing 1200 mimic displays and 600 objects in PcVue SCADA. In fact, PcVue provides one of the industry's easiest-to-use and configurable graphical user interfaces. Developers and engineers are able to configure screens quickly, thereby reducing the costs to configure and deploy applications. This is particularly true for large-scale SCADA applications, such as CERN. Most user interfaces use a tree structure method in the configuration process. PcVue takes a different graphical approach, developing an innovative configuration environment to produce real-time animation that quickly and easily allows graphical objects to be replicated and reused simply with a couple of key strokes. PcVue's configuration technology is built into PcVue SCADA for visualization of processes and real-time data and has provided CERN integrators a way to develop applications for CERN to get their applications up and running faster.
Application development is a key differentiator in PcVue's choice as a vendor. Through this method, it is able to offer the development of a unique application that can be deployed as a server application or a client application. Among the remarkable features available in the PcVue software are HDS (Historical Data Server) archiving, which controls the interface between the supervision system and the archives database, or the support of the terminal server. Because of the Windows function on the terminal server, several PcVue sessions can be used on any given station. The LHC application makes this especially appealing in utilization terms and deployment flexibility because the site is immense, and there are many users connecting to the application.
An even greater feature in facilitating deployment and reducing operating costs is PcVue's support of the VMware virtual environment. The virtual arrangement allows several operating systems to run independently from each other on a single machine as if they were running on separate physical machines. The simple process of copying and pasting an existing virtual machine onto the central PC can add an extra virtual supervision workstation. Virtualization can simulate generally underused physical machines by allocating their resources.
In the case where the process is modified (change of rate, new needs, etc.), the operator just has to acknowledge and adjust the resources the central PC allocated to the virtual machine that has been affected 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.
The result of this virtualization is that the LHC's ventilation supervision system requires just two physical machines. Each of these has 12 GB RAM and six 250 GB hard drives. The workload is also shared between the redundant physical servers. The first PcVue server allows functionality of the web server (for users to connect online) and the database server, which holds the data, while the second PcVue server maintains the terminal server.
There are a total of eight on-site monitoring stations, which are distributed one per experimental area. Each station is equipped with a touchscreen for the local maintenance operators to use. These stations are critical and are set up as intervention areas. They are located about 1 ¼ miles apart from each other and permit access, allowing the user to control the ventilation installations in the event of an emergency or any critical issues that would need to be addressed in a timely manner.
PcVue, Assystem France, and CERN have cooperated in the past, finding complementary working styles. "The responsiveness of the service and competence of technical support with respect to the end users' needs have proven beneficial," explains CERN's Mario Batz. And with over 40,000 licenses installed to date, that is a pretty powerful experience.