Oven - Problems with RCCB

post from CR4 - Recent Forum Threads and Blog Entries on 11 June 2007 06:41:11 AM. © CR4 - Recent Forum Threads and Blog Entries

My son installed a domestic oven about one year ago and the earth leakage detector (RCCB) has started to cut out after the oven has heated. He has had...

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Need Example for design Calculation Pressure
Vessel

post from CR4 - Recent Forum Threads and Blog Entries on 11 June 2007 06:13:26 AM. © CR4 - Recent Forum Threads and Blog Entries

Dear Sir, i very interested to learn hoe to design the pressure vessel according to ASME code. so i need example to study. please assist me in th...

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transmission

post from CR4 - Recent Forum Threads and Blog Entries on 11 June 2007 05:53:24 AM. © CR4 - Recent Forum Threads and Blog Entries

Why in transmission voltage always in multiples of 11? Please anybody answer me.. Regards,

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Amplified Radio Signal Without a Capacitor

post from CR4 - Recent Forum Threads and Blog Entries on 11 June 2007 05:12:39 AM. © CR4 - Recent Forum Threads and Blog Entries

hullo guys. what would happen to an amplified radio signal if the capacitor in the output channel of the amplifier was removed?

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What to Expect from a Midsize PV System

post from Photovoltaic systems and renewable energy on 11 June 2007 04:40:00 AM. © Photovoltaic systems and renewable energy

As I continue to add to my PV system, I look forward to the day when I can stop describing it as small. My short-term goal is a system large enough to get me comfortably through an extended power-outage, and lower my electric bills all-year-long. Perhaps someday I can disconnect from the grid entirely, but that?s a long-term goal. Nevertheless, my system becomes more useful with each upgrade. With these things in mind, it?s interesting to take a closer look at the system I hope to have in the not-too-distant future.

I Have:

4 ? 85 Watt Solar Panels
1 ? Morningstar SunSaver 20 Charge Controller
4 ? 105ah Deep Cycle Marine Batteries
1 ? 1100 Watt Exeltech DC to AC Sine Wave Inverter

I Want:

8 ? 85 Watt Solar Panels
1 ? Morningstar TriStar TS-60 Charge Controller with meter
4 ? S530 Rolls 6v 400ah Batteries
1 ? Xantrex 2500 Watt Sine Wave Inverter

Additional items include mounting hardware, wire, a lightning protection device, fuses, and perhaps a breaker box or combiner. I hope to become grid-tied eventually, but I?ll avoid that discussion at the present time for the sake of simplicity. To examine the capabilities of the system I hope to have, let?s start with the solar panels.

Under ideal conditions, the eight panels will generate 680 watts. A somewhat more realistic estimate would be 600 watts for 4 hours per day in my geographical location, or a daily production of 2400 watts. This, of course, will vary from day to day and season to season. Next, let?s look at the battery bank.

Because I've selected six-volt batteries, I'll connect the four of them in series to create a 24-volt system. As a result of using batteries better suited for solar power systems, and by changing from a 12-volt system to a 24-volt system, I'll expect a performance increase.

Since the solar panel array is able to produce 2400 watts per day, it follows that a constant 100 watt load would fully use the solar-produced power. Stated another way; 2400 watts divided by 24 hours equals 100 watts per hour. To allow for conversion losses, we?ll assume that only 85 watts is available on a continuous basis. That brings our daily total to 85 times 24 hours, or 2040 watts per day. This power can go a long way if it?s used wisely. This is how I might use the available power during a grid-power failure:

3 ? 13 watt cf bulbs ? 39 watts ? 4 hours per day = 156 watts per day
2 ? 19 watt cf bulbs ? 38 watts ? 2 hours per day = 76 watts per day
1 ? Chest-type freezer ? 34 watts (avg) ? 24 hours per day = 816 watts per day
1 ? Radio ? 5 watts ? 4 hours per day = 20 watts per day
1 ? Portable Color TV ? 60 watts ? 2 hours per day = 120 watts per day
1 ? VCR or DVD player ? 40 watts ? 2 hours per day = 80 watts per day
1 ? Fan ? 25 watts ? 4 hours per day = 100 watts per day
1 ? Microwave oven ? 1000 watts ? 0.20 hours per day = 200 watts per day
1 ? Toaster ? 850 watts ? 0.10 hours per day = 85 watts per day
1 ? Vacuum cleaner ? 750 watts ? 0.20 hours per day = 150 watts per day
1 ? Blow dryer ? 1000 watts ? 0.10 hours per day = 100 watts per day
1 ? Laptop Computer ? 25 watts ? 3 hours per day = 75 watts per day
1 ? Cell phone charger ? 25 watts ? 1 hour per day = 25 watts per day

Alternatively, I can use power from this system to run the motors in my corn-burning stove. Should a grid power failure occur when outside temperatures are low, I?ll gladly opt for heat, instead of using other appliances on the list. I might also use more of the available power for fans to keep cool in the summer. During mild weather, when I don?t need extra heating or cooling, the surplus power can be applied to more frivolous uses. Remember, this modest system was not designed to meet the electrical needs of the average American home.

The Xantrex inverter upgrade offers several advantages:

1. Its higher capacity allows me to run heavier loads, and to run several devices at the same time. I should be able to charge my PHEV (plug in electric hybrid vehicle) with it. My Exeltech inverter has trouble powering devices like my washing machine, and would probably be inadequate for recharging the PHEV.

2. The Xantrex inverter can be set to use power from the PV system until battery voltage drops to a preset level, and then switch to utility power. This allows me to get the most from my PV system while protecting my batteries from over-discharging, and minimizes my grid-supplied electrical consumption.

3. The Xantrex inverter will be connected to my existing home wiring, and can automatically take over in the event of a grid power failure. Eliminating the need to run extension cords when the grid power fails is a bonus.

Because I'll be adding solar panels, and because I'll be changing from a 12-volt system to a 24-volt system, I'll need to replace my present charge controller. The Morningstar TriStar TS-60 meets all of my requirements, and it allows me to better control battery charging. The digital meter option not only measures array and battery voltage, it displays additonal system information not currently available. I'll also be able to remotely monitor system statistics via the Internet.

An off-grid home or cabin with a PV system of this size would probably have a gas-powered refrigerator and stove, and additional capacity will be needed to accommodate appliances such as a clothes washer and dryer. While this system may not seem to provide a lot of power for its cost (about $6500), imagine what life would be like without it.

John

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Three Phase Output Question

post from CR4 - Recent Forum Threads and Blog Entries on 11 June 2007 03:45:04 AM. © CR4 - Recent Forum Threads and Blog Entries

Can somebody tell me how a three phase supply is obtained(output) when the input is single phase in an online UPS or a variable frequency drive ? Pl.h...

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Electrical

post from CR4 - Recent Forum Threads and Blog Entries on 11 June 2007 03:45:04 AM. © CR4 - Recent Forum Threads and Blog Entries

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Academic rebellion

post from Sciencebase Science Blog on 11 June 2007 03:00:51 AM. © Sciencebase Science Blog

Science nature microsoft Science is revolting! A revolution is underway and the battles are taking place on the Microsoft Office frontline. Science, the journal of the America Association for the Advancement of Science (AAAS), is ditching support for Microsoft format office documents. In its notice to authors it advises that:

“Because of changes Microsoft has made in its recent Word release that are incompatible with our internal workflow, which was built around previous versions of the software, Science cannot at present accept any files in the new .docx format produced through Microsoft Word 2007, either for initial submission or for revision. Users of this release of Word should convert these files to a format compatible with Word 2003 or Word for Macintosh 2004 (or, for initial submission, to a PDF file) before submitting to Science.”

There is also a warning that Microsoft Word 2007 is no longer acceptable in revision documents because of problems with incompatibilities with Equation Editor.

But, it is not just hefty Science magazine, Nature has also weighed into the battle:

“We currently cannot accept files saved in Microsoft Office 2007 formats. Equations and special characters (for example, Greek letters) cannot be edited and are incompatible with Nature’s own editing and typesetting programs.”

Thanks to An Antic Disposition for bringing the S and N issues to our attention. But, is this the only evidence of a rebellion? Certainly not. While Science and Nature are ditching the various Microsoft proprietary formats for technical reasons but staff and students at Imperial College London are truly up in arms over the imposition their institution makes on them to use Microsoft products.

The Software Freedom for Imperial College is hoping to persuade IC to implement a college-wide policy that ensures students are not coerced into purchasing M$ products in order to complete their studies. At present, many tutors and professors ask for Word format files, Powerpoint presentations, and Excel spreadsheets. All of which are infinitely more expensive than the Open Source equivalents of these Office products which are widely available and widely accepted in many quarters.

The movement also hopes to discourage the use of Microsoft products for email attachments and to preclude Microsoft’s awful winmail.dat (workaround here). They want IC to ensure that all web services are standards-compliant and fully functional in all major web browsers, not just the dreaded IE. And finally, they want to see the use of free and open source software for services when high quality and reliable alternatives exist.

Several top universities have already made the move to OS and ditched Microsoft either completely or partially. In fact, IC is the only one of the Top 20 academic centres of excellence around the world that still uses a proprietary web server that is not 100% standards compliant. This resulted, according to the site in 313 errors during testing compared to University of Cambridge: 0, University of Oxford: 0, MIT: 0, and Yale University: 1 error. SFIC hopes to negotiate with IC to rectify the problems. The main issue is probably inertia, even within academic science, Word, Powerpoint, Internet Explorer, Outlook, are all considered pretty much standard the world over.

There are viable and better, free alternatives to almost all Microsoft products, such as Thunderbird email, Firefox, Safari, and Opera web browsers, OpenOffice etc etc as well as countless non-proprietary server systems.

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http://www.sciencebase.com/science-blog/academic-rebellion.html

Maybe they all rolled three "1"s for Intelligence

Oh, crap. Tristero throws me into despair with this sad quote.

Science is a gift of God to all of us and science has taken us to a place that is biblical in its power to cure," said Speaker Nancy Pelosi, Democrat of California, arguing for the bill's passage. "And that is the embryonic stem cell research."

And here I've got a "Pelosi '07" bumper sticker on my car. How could she say something so idiotic? None of the Democrats are meeting my minimal standards for competence so far.

Read the rest of this post... | Read the comments on this post...

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Experimental Chrysler 300 Delivers 41 mpg

Warren Brown / The Washington Post in the Detroit News - Brown averaged 41 miles per gallon on the highway driving the CRD 325 miles, at speeds ranging from 60 to 70 miles per hour. The full-size 2007 Chrysler 300 V-6 CRD sedan is equipped with a three-liter, 215-horsepower, direct-injection diesel...

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