Top 5 Reasons to be thankful for AC power

During the holidays, it is often a time of reflection and giving thanks for all of the wonders in our lives. One which is very dear to me as an “Electrical Engineer” is electricity, which gives my profession a reason for staying up all night studying differential equations and Laplace Transforms!

With that said, electricity, which can be defined as the flow of electric charge, comes in several forms. But for this blog installment, I would like to focus on electric power – or the flow of electric current used to energize machinery.

Without electric power, it is conceivable that much of the world would suffer greatly. We depend on electric power to run our factories, transportation systems, and irrigate our crops. Oh yes, let’s not forget – to charge our cellular phones so we can text our buds. For this season, I give you this tribute to electrical power – but not just any electrical power… alternating current or AC power.

At the end of the 19th century, a battle was being fought between Thomas Edison (sponsored by J.P. Morgan) and George Westinghouse (working with Nicola Tesla). Tesla’s idea was to use AC current for transmission, which could easily be stepped up to higher voltages to reduce wire losses. It was the 1893 World’s Columbian Exposition (The 1893 Chicago World’s Fair) that became the tipping point for these two geniuses. For the first time, the fair was completely powered by AC electricity generated by Westinghouse equipment. Without further ado, here is my tribute to AC power and the top 5 reasons for being thankful that Westinghouse and Tesla won the war of the currents!

5) You don’t need to live within a 2-mile radius of a power plant.

AC current is easily transformed to higher voltages, lowering the wire losses, and allowing much greater transmission distances.

4) You can afford more than one motor.

Electric motors were so expensive at the turn of the century that people could only afford a single machine. The introduction of cheaper induction motors made it possible to own more than one! Vendors of early electric appliances understood this. If you owned a KitchenAid Stand Mixer, there was a power hub found under a cap in the front. This was to drive additional equipment, such as a meat grinder or a pasta maker. The mechanical interface has not changed in over 100 years.

3) Life is more productive.

With electric power distribution reaching far into the country, along with the invention of the incandescent light bulb, working (and playing) hours were extended beyond sunrise to sunset. Now, people could be active earlier or later in the day or for longer periods during the shorter winters.

2) Life is safer.

Prior to electric light, kerosene was used for lighting. Industrial moguls such John D. Rockefeller made their fortunes selling (and transporting) kerosene used for lighting. One accidental spill of a lamp and a fire could quickly start. It was the switch to electric light that drove the industry to find new uses for the products refined from crude oil – namely gasoline, once a waste by-product that was burned off in the production of kerosene.

1) Life is cleaner.

With the invention of AC induction motors and the availability of power to run them, industry moved from burning coal to power steam engines to running machinery with electricity. Now, one single power generation facility, such as Niagara Falls, could power entire industrial complexes.

So there you have it … my top 5 reasons to be thankful for AC power and all the wonders it brings to our lives!

For more information on utilizing this amazing technology, visit our power management page or start your new design using WEBENCH®. Till next time….

  • My apology for previous improper data in my previous comment:

    The penetration depth at 50 Hz (60 Hz) is in tenths (not tens) of centimeter for metals used as conductors; specifically for copper it is around 9.2 mm and  somewhat more for aluminum.

    The conductors for MVA HV AC transmission lines are stranded aluminum wires, which themselves form a „skin“ around a steel core. The losses due to skineffect are thus reduced significantly.

  • "top 5 reasons for being thankful that Westinghouse and Tesla won the war of the currents!"

    One very important point should be added:

    To transfer the same power, less copper (nowadays aluminum) paradoxically  is required for AC transmission line, as compared to DC line. Factor of benefit is sqrt(2):1 for AC to DC; if we assume the same peak voltages values and the same values of effective currents per conductor. It stems from the fact, that sum of 3 AC phase currents for equal phase loads gives zero and thus neutral (fourth) lead is not needed. You indeed see just 3 wires per system on long-distance, hundreds of MVA HV AC transmission lines. The skineffect plays a little role here as the penetration depth for copper for 50 Hz (60 Hz in US) is several tens of centimeters and even somewhat more for aluminum.

  • Actually, DC power transmission and distribution is having a renaissance... it took developments in high power solid-state electronics to make it happen, but there are a few advantages for long hauls. HVDC only requires two wires (instead of 3 for AC), has no skin-effect (so the conductor is smaller) and doesn’t require synchronization with other plants.  The capital equipment cost for HVDC transmission is higher, so for short hauls, AC still wins the economic war. There is also a push for local 48V systems within the home too… mostly for lighting since LED lighting requires constant current.  

    So maybe Edison’s DC wins in the end…

  • Is AC still so wonderful now that power electronics is widely used? I wonder if power would be distributed using DC if we could design the system afresh today.