B513 Planning Meeting, 28th May 2003

Present:           Tony Cass, Anne Funken, Jukka Lindroos, Jose Miranda Vizuete, Tim Whibley

1.             Previous Minutes

  1. 2.1c) There will be no filters in the air intake.Jukka commented that it would be possible to place a smoke detector in this air inlet which would shut the fire dampers just as in the case of a fire in the LV room.

2.             Substation Planning

  1. The substation tender was issued on schedule and some companies have contacted Jose for further details.
  1. Now that the hvac arrrangements are defined, Anne will contact Denis Raffourt concerning the smoke detection details. It was noted that there is no urgency in this area as it is a fairly standard installation. However, an estimate should be prepared.

3.             Barette Protection

  1. Anne commented that all equipment must be equipped with an internal fuse to protect against damage. Fuses at either the normabarre connection or barette level are to prevent damage to cables, not to equipment.
  2. Ideally, there should be no requirement for a fuse/breaker at the barrette level provided that the sum of loads on the individual sockets is less than the rated power for the internal cabling and the cable connecting the barrette to the normabarre. However, this cannot always be assumed and so it is safest to have a fuse/breaker at this level even if there is no strict requirement. An additional advantage is that if there is any problem, it is easier to reset or replace the fuse at the barrette level than to have to replace the fuse in the normabarre connector under the false floor.
  3. In terms of the breaker vs. fuse choice, we should anyway make sure that the inrush currrent for the equipment connected to the barette stays within the rated load. On this basis, a breaker has the advantage in terms of ease of reset. It was noted, however, that the remotely addressable power bars that we are considering are equipped with fuses.
  4. If we are to limit the number of systems connected to a normabarre to maintain the inrush current below the barrette rating, a maximum of five of the current disk servers can be connected per 16 A normabarre. In principle, it ought to be possible to connect 13 CPU servers per barrette, but these have a maximum of 10 sockets.
  5. Tim noted that, given the many barrettes required to support the multiple independent power supplies, the placement of the disk servers is determined by the availability of normabarre connections.
  6. In response to a query raised during the discussion of remotely addressable power bars, Anne stated that the normabarre connection supports a current of up to 63 A.

4.             Machine Room Planning

  1. Anne, Nigel and Tony have discussed a room layout that places equipment racks back-to-back in 18 m long rows in three blocks in the machine room. Each row contains six “Mario racks” or up to 18 19” racks. Although the rows are 18m long, they will be supplied by two 9 m normabarres placed end-to-end. This is based on the measured power consumption of
    1. “old PCs”: 100 W per PC with a power factor of 0.7 where each 100 A normabarre is limited to a useful capacity of 50A/phase and can support 3.5 “Mario racks”, and
    2. “new PCs”: 200 W per PC with power factor correction allowing the use of the full 100 A/phase normabarre capacity.
  2. Based on recent experience, and given recent changes to European standards for PC power supplies, we consider that it is reasonably safe to assume that power factor correction will be available on all future systems purchased. On this basis, we do not need to allocate space for filters in the PDUs and each PDU could therefore support up to 6 normabarres. Given the room layout proposed and to allow some scope for future expansion, we will install one PDU per double row of racks, each PDU supplying four 9 m normabarre lengths and one 18 m normabarre length. Twelve PDUs are required to support the physics equipment and the operators area.
  3. It is proposed to locate critical equipment in a strip about 5 m deep along the back wall of the machine room. One or two PDUs in tis area would be required to supply both the normal power and the diesel backed power through multiple 3 m normabarre lengths. The PDUs in this area would also be used to supply the modem/fibre rooms in the Salčve side corridor.
  4. Anne will discuss the proposed layout within ST/EL to establish the possibilities for reusing the existing normabarres and will then contact the contractor to establish an estimate. It was considered that the installation work could start from September.
  5. Jukka commented that we must be careful if racks are placed back to back. Experience in the vault has shown that convection cannot generte the air flow necessary to keep the temperature at a reasonable level; perforated tiles are needed to generate a forced upward air flow. This reinforces the view that we should be converting the hvac arrangements in the machine room to create an air flow from the false floor. Unfortunately, planning is still at an early stage and will take some time to complete given the lack of drawing staff in ST/CV. Fortunately, the ducts would natrually be placed along the north and south walls of the room whilst most of the PDUs would be along the east and west walls.
  6. Given the shortage of planning staff in ST/CV and other projects, Jukka considered that work on the chilled water piping in B513 would not be possible until the winter of 2004/5. Other work, such as the installation of the necessary duct work and modification to the cooling stations, could in principle be done at any time as the current equipment is never fully loaded. However, Jukka felt that even if this was possible in principle, the ST/CV staff situation would push the work to 2005.
  7. Tim will contact Steel Systems to see if they can still provide perforated tiles in the required 61cm x 61cm format. If these tiles aren’t easily available we could consider grids between the back of racks, but not in the corridors. Jose considered that the perforated tiles would cost 150-180 CHF/m2. The current layout has 200 m2 of perforated tiles for a total cost of 30-36 kCHF

    8.
  8. Jose has investigated the level of separation between the machine room and the rest of B513. This has shown that the open part along the back corridor extends only across the width of the modem & fibre room; the division extends under the corridor on either side of this area. Although the machine room is completely isolated around the false floor plenum, the separation is only by wooden barriers and there is no insulation where cables pass through. Thisis probably not adequate in terms of fire protection. Jose will contact Fabio Corsanego and use the opportunity to clarify the status of the separating wall between the machine room and the barn.

5.             AOB

  1. The formal reception for the hvac units in the vault took place on Wednesday. There are some points to address, but the units are now considered as being fully in service and to be handled by the general ST/CV operations team.
  2. Tony will be giving a further presentation of the B513 upgrade status to IT division at 9:30 on June 27th. The presentation will cover the substation status, including failure modes for the electrical supply, and the initial planning for the machine room upgrade.
  3. Next Meeting: 2pm, June 10th in B31-1-012.