AC power transmission losses are greater than DC losses. That is hardly an industry secret. In fact the reason you can wirelessly charge a cell phone is because any changing current will radiate away some energy. You just need to coil the wire up to gather some of that energy in a convenient place. At the Three Gorges Dam in China, high voltage DC transmission lines were chosen to bring the power to the people for a variety of reasons. Many power companies are now starting to rethink the decisions that made AC transmission the obvious choice in the previous era.Depending on the voltage, wire characteristics, and environment, other parasitic losses in AC transmission can become insidious, much more so than the relatively small radiative loss. At a mains power frequency of 50 or 60 hertz, the skin effect — where the majority of the current travels only on the surface of the conductor — starts to become more important. If most of the current is travelling in only a portion of the total cross section available, it will see an effectively higher resistance.

To combat the skin effect, more expensive, multi-stranded wire must be used. Capacitive coupling to the ground and other objects also sap some energy from AC. You can think of this effect as being like a football player running out on to the field at the start of the game and the numerous hands of fans rising up along the way to high five him, slowing him down a bit. The numerous hands are charges of opposite polarity inside of other elements in the surroundings that feel the attractive force of charges in the wire.So why do we use AC? To begin with, it typically comes hot off the presses as AC. In other words, it is most efficiently produced in this form by three-phase-alternators at the power station’s turbines. If you then want to transmit power any significant distance from the point of generation, you need to step up the voltage quite a bit just to get something worthwhile on the other end. If, for example, you are starting with 20 volts and are dropping one volt every mile because of the resistance of the wire alone, 20 miles out you will have next to nothing.

Actually the losses will diminish a little less than linearly but you get the idea. Transforming to higher voltages is simple for AC, you use a transformer — but for DC, it typically means using motor-generator sets or other fancy elaborations. portable ac units searsWhen you then manage to get some power transmitted, your biggest customer might very well be a large motor that compresses, pumps, or other moves stuff, and runs on — you guessed it — AC power. vw beetle ac compressorThe three-phase AC induction motor, first envisioned by Tesla, is far and away the most efficient way to convert electricity into mechanical power. amana ac units ratingsDC motors, until recent times, required graphite brushes for commutation which severely restrict maximum RPM, reliability, and lifespan.

It may be worthwhile to make a quick comparative note on power generation in automobiles. A long time ago cars used DC generators in their electrical systems, but today they use AC alternators almost exclusively. This may seem a bit strange to the casually informed observer because a generator can charge the battery directly, without need for rectifier diodes to convert AC to DC. In practice, generators do not work as well since cars need to extract electrical power across a range of engine speeds, from idle to redline. Since alternators create their magnetic field with a “field current” instead of magnets, they can change this field according to need and optimize the alternator function. So in this case, the intuitively obvious solution, using a DC generator, is not necessarily the best solution.Next page: Voltage is kingThe requested URL /store/index.php?main_page=index&cPath=11_66_71 was not found on this server. Cut-Out (Drill Size mm) Plugtop Power Supplies - Fixed Output Voltage

12v power supplies are a core part of the extensive range of power conversion products that PowerPax offer. We have one of the largest ranges of 12v power supplies available and offer many types of power supplies with a 12vdc output. The ranges below all include power supplies which offer a 12vdc output. once you click into one of the range boxes below you will see a number of drop down boxes on the page. Please make a selection from each drop down box to configure your 12v power supply. Once you have done this you will be provided with full details on your selection and where possible a link to the product on our distributors website Alternatively please contact PowerPax for details on our range of 12v power supplies Content on this page requires a newer version of Adobe Flash Player. March 2013 - SL Series of DC/DC Converte Cooper Bussmann Announces New Martek SL Series for Single Output DC/DC Conversion Eaton and Cooper united Eaton and Cooper - united to power more possibilities

Eaton’s electrical business is a... Aug 2012 - CPCIR Series Released Martek Power Announces Compact PCI Power Supply for On-Board Railway Applications. June 2012 - Martek Power/Abbott Appoints TTI, Inc. as Global Distributor for Military Power Management Aug 2011 -VER series of DC/DC Converters from Martek Power Provides Up to 100W for Railway Applications. July 28, 2011 - Cooper Industries Announces Acquisition of Martek Power - Acquisition expands power conversion applications to key... July 2011- Martek Power joins the United Global Compact in respecting human rights. June 2011- Martek Power targets Aviation with new MW75S -- AC-DC Power Supply with Power Factor Correction May 11 - Martek Power to Showcase Latest Railway Power Supply Products At Railtex 2011 Apr 2011- Rugged MIL/COTS power supplies from Martek Power's Abbott product line to be exhibited at IDEF ... Mar 2011 - JL Series DC/DC Converters

for rail now includes Conduction Cooled versions Feb 2011 - Alain Picard, R&D Director of Martek Power Europe, receives a medal for his contribution to electrical engineering in France. Feb 2011 - Martek Power IRIS certified Based on ISO9001, the IRIS standard takes into account the specific requirements of railway... Jan 2011 - New railway power supplies with very wide input voltage range and up to 50 watts of output power. Dec 2010 - Martek Power Laser Drive plans to exhibit lamp & laser power supplies at Photonics West 2011. Nov 2010 - New 1U 650W AC Front End power supplies boost over 92% efficiency Sept 2010 - New rugged dc/dc converters from Martek Power Powertron JL series expanded output power range for railway usage. July 2010 - Laser Drive Inc. acquiredLaser Drive is a company specializing in various power supplies for laser and... July 10- New Power Supplies at Innotrans Martek Power new railway power supplies at Innotrans (Sept 21-24).

July 2010 - New UK Disti for MIL COTS power products joins Martek Power at Franborough International Air Show. June 2010 - Switching power supplies in DC/DC drive automotive's Energy Recovery System. May 2010 - New DC modules EN50155 ready New 25 W rugged power supplies: MBRH series by Martek Powertron are EN50155, RIA12... Apr 10 - Martek Power Implements Oracle E-Business Suite in N. America Operations Apr 10 - Martek Power selected as Raytheon Preferred Supplier - A world leader in linear power supplies and switching power supplies. Feb 2010 - ISO 14001 certification achieved by Martek Power France - maker of worldclass LED power supplies, lighting power... Feb 2010 - 1200-1500W Telecom PSU T-series Datacom and telecom front ends rack mount power supplies. Dec 09 - CMR120 DC Module New 120 W DC-DC power supplies for railway meets EN50155 standard. Nov. 2009 - 200UFR Standard power supplies for telecom;

compact, low noise 2 Watt dc-dc converters with wide... Oct. 2009 - Martek Power appoints new power supplies distributor for the Russian Federation. Oct. 2009 - Raytheon Honors Martek Power in Supplier Excellence. Sept 2009 - Fangyuan Electronics Co. Ltd added to the Martek Power Sales Representative Network Aug 2009 - PF100 series New 100 Watt Mil/Aerospace PFC Power Supplies meets EMI (CE01, CE101) without any EMI... Martek Power unveils redesigned web site on switching power supplies and linear power supplies June 2009 - Martek Power is the new name May 2009 – SEMELEC Acquisition MARTEK POWER acquires SEMELEC March 2009 - AC-DC power supplies with 400W output for MIL apps- MW400S Switching power supplies with Active PFC... Nov. 2008 - Two new 2W RoHS Compliant board mount DC-DC converters Nov. 2008 - Martek Power (USA) (leader of making power supplies in aerospace grade) achieves AS9100:2004 Rev B Certification

Sept. 2008- 200WFR and 200LFR 2W low profile, board mount DC-DC converters ideal for telecom, computing, industrial and... July 2008 - 1500UFR 15W industrial DC-DC converter with wide input range May 2008 - CB75T COTS Modules Rugged aerospace and military power supplies (switching power supplies) with 75 W, Triple... Feb 2008 - CB150D, CB225T High density multi-channel MIL grade COTS DC-DC converters from CB series Martek Power designs and manufactures a wide range of switching power supplies and linear power supplies.  They include standard, semi-custom and custom AC-DC power supplies, DC-DC power converters, DC-AC power inverters and EMI filters for Military, Aerospace, Medical, Railway, Automotive, Computing, Data storage, Telecom, Networking, Instrumentation and Industrial applications. Our switching and linear power supplies range in output power from 1 to 50,000 watts. We have extensive expertise in power supply design, engineering, and manufacturing and are well versed with a variety of industries' specific requirements and the most demanding quality needs.

And, with our broad range of field proven standard power supplies, we are capable of providing unique custom power solutions that meet special requirements of our customers worldwide in all market segments we serve. LATEST NEWS: Eaton's electrical business is a global leader with expertise in power distribution and circuit protection; structural solutions and wiring devices; solutions for harsh and hazardous environments; Eaton is positioned through its global solutions to answer today's most critical electrical power management challenges. Eaton is a power management company providing energy-efficient solutions that help our customers effectively manage electrical, hydraulic and mechanical power. A global technology leader, Eaton acquired Cooper Industries plc in November 2012. The 2012 revenue of the combined companies was $21.8 billion on a pro forma basis. Eaton has approximately 102,000 employees and sells products to customers in more than 175 countries. Are you an existing customer ?