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#11 |
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Account Disabled
Join Date: Apr 2003
Location: US
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semiconductor fabrication is a dying breed in the US, thanks largely to environmental regulations and lawyers. The chemicals used in the fabs are largely unknown in terms of their toxicity (?). IBM just got off a lawsuit in CA (Santa Monica I think) by its employees who developed brain tumor. A couple of others are pending in NY (East Fishkill).
Everyone in the industry is watching that very closely. If IBM loses, it will have a huge negative impact on the industry and may speed up the move offshore. |
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#12 | |
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diyAudio Member
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Quote:
---Gary |
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#13 |
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diyAudio Member
Join Date: Jun 2001
Location: Alexandria, VA USA
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As David pointed out, 5 nines has been the standard, but going out to 6 is happening more often. A national broadcaster here local has a well built example I will outline.
It first starts out at multiple streetfeeds - 3 in this case, so that one can be taken out for service and still have a backup (DC has a really crappy power grid. Each summer manhole covers are thrown a hundred feet in the air as the cables they cover explode ). This then goes into the transfer switch which looks at the shore power and the 4 rather large gensets - 1600hp each. Only 2 is required for the entire load, so they have a signficant backup there also. As the gensets are already kept warm, they can start and stablize in about 5 seconds - take a full load in about 10. If the shorepower should fail, drop a phase, brown-out, drop freq below a set number or some other failure mode, the gensets are started and switched. Now inside the building, the building is divided up into three systems. One is electrical you can afford to lose. THe second system is things that can afford to drop for a few seconds, such as the HVAC system. The last system is for those things that cannot lose power at all. These are always connected to the inverters - which are connected to a huge room full of batterys in the basement. They are always fed from this system and are not directly connected to the usual electrical system. If street power fails, things connected to this system never notice. The batterys have the ability to run the system for about 4 hours. But as David mentioned, without cooling, this place is in serious trouble fast. As we all know, an amplifer without cooling is shortlived - and computers too. So in reality, almost all of the building's power needs are protected in some fashion. Now, such a system can actually save you money too - it by design will correct your power factor. Which given all the inductive loads otherwise, this will save you money. How much depends on your local power company rates. Two - it can peak shave. If the power company can call you up in the heat of summer and ask you to drop off the grid and use your gensets, they will reduce your power bill by a *very* large number. Why? In the case above, it means that they don't have to build very expensive peaking units to supply the couple of megawatts the building would need otherwise. Peaking units are expensive to build, expensive to maintain, and expensive to fuel. These systems are pretty cool. Expensive. The local Reuters shop replaced its batterys a year or two ago - several hundred big lead acid lumps had to be hauled up to the penthouse floor - which was not served by a elevator. But it sure is nice to work in a building with one of these. |
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#14 |
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diyAudio Moderator Emeritus
Join Date: Jan 2002
Location: Michigan
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You guys are awesome. Many thanks.
__________________
Rodd Yamashita |
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