Computers have become a permanent element in human life, creating dozens of petabytes per year. For all this information to make a little sense and to be useful, it needs to be processed and in this manner the importance of the powerful GRID networks takes affect. The GRID is made up of thousands of servers throughout the whole world, linked by fibre optic circuits and controlled by specific software.

The GRID room project, responsible for the FCCN, LIP and LNEC partnership, will shelter up to 2,000 servers, consuming around 350 W in every 200 m² space. This project created two big challenges: to electronically supply 2,000 computers and disperse the heat generated by this equipment in a rapid and efficient way.

Electronic Installation

The solution for the electronic installation was defined by a scaled system, energy efficient and immune to the harmonic currents that will be felt, originating in the exchange sources of the computers.

In the exterior of the building a transformer point, equipped with 2 transformers of 1,000 kVA and two group generators, one of 800 kVA and another of 630 kVA will be installed. Each of these pieces of equipment will supply phase 1 and phase 2 of the room, or in other words, two independent installations that are connectable to the QGBT level (without energy source parallels). In this way it is possible to start with an installed electrical value of 1,000 kVA and evolve in the future to support the final total of 2,000 kVA.

In the interior of the room the installation of two systems of 24 hour energy supply (UPS) is foreseen. One of the systems will be of 400 kVA (two UPS of 200 kVA) that will supply the calculus servers and the other system will be 200 kVA (one UPS of 200 kVA) that will supply the command and process control servers. The 3 UPS will be the same, facilitating the works and maintenance costs. The 200kVA system will be helped by the generator group, but the 400 kVA will not, serving only to provide energy during the necessary minutes for the correct switching off of the computers in case of an energy failure in the energy network. The UPS for installation present yields of up to 98% and harmonic tensions of no more than 3 %.

The commuted sources of the installed servers will be responsible for a large quantity of the unidentifiable harmonic currents at this point, as the servers will have distinct origins as a type of energy source that will respect the market rules of consumption, or if you like, the cheapest that exist at the time. The unknown quantity of the harmonic frequencies present in the installation, as well as the requirements of energy efficiency, make the usage of harmonic filters impractical, be them passive or active. It is necessary then to significantly reduce the size of electrical piping in the installation in reference to harmonic currents, in a way to avoid the appearance of harmonic tensions in the installation.

The reduction of the size of the circuits is managed through the use of mono-polar cables of reduced sections, increasing the number of conductors and maintaining the conductor section neutral to the phase conductors section.

The increased number of cables (each UPS is created using 16 cables of 50 mm²- 4 for every phase and neutral) creates the necessity for an adequately fixed system, with weight limits up to 200 Kg/m, which in the project were distributed in 6 cable routes.

AVAC

The challenge given by the partnership responsible for the handing over of this project to Graucelsius was used to show that a project with few criteria related to energy efficiency could still bear in mind the demanding requirements of this field; without however, avoiding the remaining aspects directly linked to the associated responsibility of an installation of a GRIS room.

The Graucelsius team, from the very beginning recognised the necessity to innovate and create solutions that corresponded to the high expectations of the partnership. This capacity to rework ideas and think ‘outside of the box’ is without doubt one of the key lines of the philosophy that best characterise Graucelsius’ work in the projects in which they participate.

In this way, Graucelsius opted to produce a system of simple concepts with the point of view focusing on mechanical installations, with a starting point of basic requirements of high trust and necessary flexibility in the essential system in the periods of maintenance. In this way the possibility to allow maintenance or carry out repair work in the key equipment without stopping the cooling system was seen as necessary.

The energy efficiency of this system fits especially with the energy requirements of the equipment and in the applied technology, as for example the communication that exists between various key pieces of equipment being based on SNMP protocol.

In relation to the conditioning of the space, we opted to apply the cold aisle- hot aisle system, seeing as it was additionally noted the supply system of refrigerator fluid R134a without a refrigerated circuit was necessary to allow the exchange of air with finite units applied within the informatics frames.

In this manner it is estimated that the working of this equipment within these systems allow s a powerful density per frame, between 20kW and 30 kW, values which are much higher than the configurations and densities typically applied in works of this type.