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我是資深的電腦資訊從業員,曾於 Motorola 及 Philips 等跨國大型公司管理層工作十多年,具各類ERP資源管理系統及其它應用系統經驗,如QAD之MFG/PRO、SAP、Ufida(用友)、Kingdee(金蝶)、Microsoft's Dynamic、Wonderware's In-Track (SFC)、Webplan (SCM)、Hyperion (business intelligence)、Informatics (Data Warehouse)...等等。另外,我精於廠房車間之電腦資訊運作,擁有 CISSP 及 ITIL 認證,能提供日常資訊運作之檢測及審查,以提高操作效率。 本人誠意為各類大中小型廠房提供資訊審計、支援及意見,歡迎聯絡,電郵為 au8788@gmail.com

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提供香港股票價位歷史數據

我想很多人會對"香港股票價位的歷史數據"有興趣,我已下載成Microsoft Access database version 2000 的文檔,資料由2008/1/1至2009/12/2,zip壓縮後也有11M,若索取請留你的PM我 。

祝願各瀏覽者股壇威威!

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2016年6月9日

Power Calculation for UPS Selection

Power calculations is approx as below example:
- 2 x Billion 7300GX modems 2 x (12V * 1A) = 2 x (12W) = 24W
- 1 x Linksys RV082 router (240V * 0.2A = 48W)
- 1 x 24 port HP Procurve 2524 switch (approx 36W)
- 1 x Dell PowerEdge 2850 with 2 x CPU's and 4 x hard drives (700W max)
TOTAL = 808W

Because 1.4VA = 1W (approx), those devices would consume 808*1.4 = 1131VA
Support using a 3000VA UPS, it can last for 2.6 hours (approx 3000/1131)
With a 5000VA UPS, it can last around 5000/1131 = 4.4 hours

In actual case, with respect to run time, it is not the 3000VA or 1000VA that determines your runtime – its the capacity of the batteries. You can get a 3000VA UPS with quite a small battery (= short runtime) and you can get 1500VA UPS with additional plug-in batteries for super long runtime. For example, a second hand 3000VA UPS from ebay might have the ability to support 15A of load but the shagged out batteries may give you less than 5mins of runtime. Hence, you have better check the UPS configuration from vendor web site.

3KVA is the maximum load the UPS can handle.
The AMP HOUR rating of the battery system is what determines runtime.
eg a 12V battery with a 7AH rating will run a 12V 1A load for 7 hours, or a 12V 2A load for 3.5 hours.
7AH/1A = 7 Hours
7AH/2A = 3.5 Hours
Our 12 V Sealed Lead Acid (SLA) 7AH battery has an energy density of 12V at 7Amps for 1 hour = 84Watt Hours = 5040 Joules.
except that's not quite correct because of battery aging.
In most cases, it would recommend a max of 2 hrs for commercial installs. This is because AC and lights, phone system are also off, resulting in H&S issues. For home use, it would recommend 30 min max.

Runtime Example from UPS vendor web site: