B513 Planning Meeting, 18th February 2003

Present:           Yannick Body, Tony Cass, Anne Funken, Jukka Lindroos, Jose Miranda-Vizuete

1.             Previous Minutes

  1. 2.2: The equipment load to be supported by the HVAC systems in the event of power failure was clarified as 2.5 MW for first 10 minutes with upto 500 kW in the vault. At the end of UPS battery life (10 minutes) the load drops to 250 kW with up to 125kW in the vault.
  2. 2.3c: Cables can be routed to the technical gallery through the existing openings.

2.             Substation Planning

  1. It is now clear that two 3 MVA transformers are required to cover HVAC and general service needs rather than two 2 MVA transformers. This change has no impact on the space needed in the safe room, however.
  2. Cooling 2.5 MW in the machine room requires decoupling the corridors from the machine room cooling. Individual corridor units (as in B31) could be considered.
  3. Jukka confirmed that there will be no need for access within substation rooms to maintain any hvac equipment. Access will thus be restricted to qualified electricians so there will be no need for any emergency power off system.
  4. Anne presented the general substation schematic. This made clear the exposure of the HVAC equipment to the failure of a single transformer. There was some discussion as to how this risk could be minimised but there is no evident solution as the full HVAC load must be supplied by the diesels in case of main supply failure. It was agreed that we need failure rate statistics for the transformers to understand the extent of the risk.
  5. During maintenance of switchboards, part of hvac load will be cut. Maintenance is once every 6 years, failure extremely unlikely. Need to understand impact of los of equipment.
  6. On physics side, good protection up to UPS. Dowstream of UPS, risk to lose up to 1/3rd of equipment at most. Problem is with failure on hvac side. Risk not to have enough cooling capacity to keep systems running.
  7. However, is need to maintain 18kV switchboard every 6-10 years. This leads to cut in physics load. Only avoid this today as load can be supported by 1 transfo. In future, will not be able to escape. Refusing maintenance will increase risk of failure.
  8. There has been a suggestion to route cables in the substation at ceiling level to improve the cable routing on top of the bunker. Routing at ceiling level may be possible, but cannot be accepted if there is any requirement for extra free height in the bunker (and thus to increased construction costs). It was noted that ceiling level routing also requires a detailed layout of electrical equipment layout before construction, and is thus disfavoured.
  9. Anne was anyway concerned that it would not be possible to achieve an acceptable layout of transformers and cables on the top of the bunker if all six transformers were located on the Salève side of the barn doors. It may be necessary to place two transformers on the B31 side.

3.             AOB

  1. Next meeting: 9am, Monday 10th March.