January 30, 2014

Power Supply Seminar 2012/13 Textbooks Online

Those who missed Texas Instruments latest 2012-2013 power supply design seminar can now download all the materials here. This time they archived online both the manuals and the presentations, which are quite handy. Unfortunately, TI is doing a pretty good job making it very hard to find these files in their website. If you want to read past TI (formerly Unitrode) seminar manuals beginning 1983, I listed them all here. I keep maintaining and updating these links for over a decade now. Originally I got the list of their topics (which at that time was much shorter) from one of TI application engineers who interviewed me for a job. I did not get the job back then, but I got a list of the links. It was a good deal. (-:

December 10, 2013

Thieves Stealing 200-lb Portable Generator

One of the disadvantages of a portable generator is it can be easily stolen. This video footage shows how three suspects stolen a 200-pound generator in 52 seconds.

July 25, 2013

Subaru Portable Generators Recalled Due to Fire Hazard

Robin America recalled more than 4,500 Subaru portable gasoline generators because of possible fuel leak. The recalled models are SGX3500, SGX5000 and SGX7500 . These units were made in China for Fuji Heavy Industries Ltd., of Tokyo. Read more and find affected serial numbers here.

May 19, 2013

Back-Up Power for Gas Stations in NY

Governor Cuomo proposed new legislation according to which all gas stations within a half-mile of highway exits and hurricane evacuation routes will be required to have a transfer switch installed by March 1, 2014 and  deploy a generator within 24 hours of a blackout. This requirement would apply to about one-third of all NYS gas stations.

In addition, the chains with 10 or more stations will be required to install a transfer switch for an additional 50% of their stations by March 1, 2016, and must activate a generator within 48 hours of losing power during an emergency. This requirement applies to an additional 15% of NY gas stations.

Finally, as of March 1, 2014, all newly constructed gas stations or the stations that have major renovations will be required to have a transfer switch or back-up generator installed.

Cuomo said “New York State must learn the lessons from Superstorm Sandy so that we are better prepared for the future”. Really? I wonder if governor followed the news during Sandy. The main problem was lack of gasoline rather than loss of power by gas stations. How would the stations located out of town and not connected to natural gas system fuel their generators when they had neither gasoline or diesel? Of course they could use propane generators, but again, the stations located far away from cities and towns will have hard time refilling their propane tanks during a major disaster. If the proposed bill will pass, we will pay more at the pump because the stations will pass down onto us the cost of implementing the new regulation. As usual, our governor is trying to gain cheap popularity.

May 2, 2013

Top Paying Engineering Majors in 2013

According to a recent survey, college graduates with major in Petroleum Engineering have the highest average starting salary of $93,500.

Here are the ten top majors by starting salary:

Petroleum Engineering: $93,500
Computer Engineering: $71,700
Chemical Engineering: $67,600
Computer Science: $64,800
Aerospace/Aeronautical/Astronautical Engineering: $64,400
Mechanical Engineering: $64,000
Electrical/Electronics and Communications Engineering: $63,400
Management Information Systems/Business: $63,100
Engineering Technology: $62,200
Finance: $57,400

Source: WSJ

January 6, 2013

Higher Distribution Voltage for Server Efficiency Increase

Several years ago Google suggested an open standard for desktop PC power supplies with a single 12V rail instead of multiple rails. The point was the higher buss voltage the higher overall PC PSU efficiency.

This year Google power designers are going to present at DesignCon 2013 their strategies for reducing energy losses in servers, including DC-DC regulator architectures as well as higher voltage distribution. Google apparently is going to make a case that higher distribution voltage levels improve overall conversion efficiency. Obviously, raising the buss voltage will lower conduction losses. On the other hand, switching losses in downstream DC-DC regulators will increase. In addition to this, you will need to use higher voltage MOSFETs whose characteristics generally degrade with their rated voltage. That's why it will be interesting to see their experimental results and  conclusions on optimal distribution level.

November 3, 2012

Recall of Champion Portable Generators Sold at Costco

The U.S. Consumer Product Safety Commission announced a voluntary recall of about 8,600 portable generators manufactured by Champion Power Equipment, of Santa Fe Springs, CA. The cause of the recall is gasoline can leak from the generator's carburetor, posing a fire hazard. There have been 11 reports of fuel leaking from the generators, including eight reports of the generators catching fire. The recalled model numbers are 41332 (8250 watt) and 41532 (9000 watt). These models were made in China and sold at Costco.

October 29, 2012

Hurricane Sandy- Interactive Map with Latest Information

Google has created an interactive map for Hurricane Sandy. You can zoom in the map, select a location and find the latest information on the storm location, forecast track, shelter addresses, power outages, and other related data. Just check or uncheck options in the layers menu. You can also switch between a map and a satellite view. And if you lost power, remember- never run a portable generator indoors and in direct rain.

September 28, 2012

Google and Green Renewable Energy

Google is increasingly using renewable energy. Previously they've announced their commitment to carbon neutrality in 2007. They have already invested $94 million in four solar photovoltaic (PV) generators near Sacramento, CA. (See what is PV generator and how it works). These projects have PV systems with a total capacity of 88 MW. Now Google signed an agreement with their utility to supply their Oklahoma data center with 48 MW of wind energy from the Canadian Hills Wind Project.

So, let's do a little math. Depending on the utility's territory, the green power generally costs from 0.5 to 2.5 cents per kilowatt hour more than regular electricity. Assuming the best deal, which is extra $0.05/kWh, each MWh is extra $50. Then 48 MW adds extra 50x48=$2400 each hour. Over an entire year 48 MW of green electricity may cost Google 2400x24x365=$21 million dollars more. In reality, their losses may be less because renewable energy systems rarely work at their maximum capacity. On the other hand, they can be as much as $100 million is they will be charged extra 2.5 cents per kWh. Read more about Google "green" energy activity.

August 20, 2012

China Safety Standard- Higher Clearance for Power Supplies

We used to think that if our power supply design meets IEC or corresponding UL requirements for a given application, we would automatically meet most national standards of other countries. Now, the main ITE Standard in China GB 4943.1-2011 appears to set more stringent requirements to ITE equipment. Although in general, GB 4943.1-2011 is based on IEC 60950-1 2nd addition, it includes certain deviations. Particularly, par.1.1.2 states that unless specified by manufacturer, the equipment is to be used up to 5000m altitude above sea level. Therefore, in the absence of the marking of par.1.7.2.1 specifying the altitude below 2,000 m, the equipment shall comply with the requirements for 5000m altitude. For such equipment, the minimum electrical clearance has to be multiplied by the factor of 1.48.
In many offline SMPS the minimum UL required creepage between primary and secondary circuits is 6.4mm. If both primary and secondary circuits are located on the same side of PCB, this number also determines the spacing (clearance) between the circuits. With the new China standard that goes into effect December 1, 2012, this spacing will now have to be greater than 9 mm. Note that GB 4943.1-2011 will apply to not only the devices for use in the China, but to all those produced there too. So, if you manufacture power supplies in China, in my understanding, you either need to redesign the PCB and replace certain surface mount optocouplers (if any), or add a warning label showing that your PSU is not for use above 2000m.