DC: danger alert?

May 25th, 2016 | Posted in Power quality
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The war between pro-AC fans and pro-DC fans has been around forever; ever since the end of the 19th century in fact.
Today, more than ever, the battle is raging! New technologies such as LED, cellphones, photovoltaic, and electric cars, are becoming more prevalent in our everyday lives, so it’s no surprise we’re witnessing a new major turning point in this AC versus DC battle: the pro-DC (electronic device manufacturer) fans are stepping up to the fight against the pro-AC (electric device manufacturers) who are carrying the flag for AC – which differentiates high and low current.

The quantity of videos and articles in favor of one or the other of these solutions is increasing and is about to tip the balance.

ac vs dcOn this point, the above video has caught the attention of the EEC team.

All electricians are familiar with the theoretical characteristics of these two different currents, but in practice, not many people really visualize the impact of the “zero crossing” of the voltage, every 10 milliseconds by the sine wave in the AC distribution.

For all that, could full-DC really be dangerous? What do you think about it? Are you rather pro-AC or pro-DC and why? What is the most viable solution? The most environmentally friendly? More generally, what’s your opinion on the War of Currents?

We’re currently preparing a complete document about this top confrontation. Help us writing it if you have information about this topic. Each volunteer will receive this exclusive document for free!

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Comment(s) to “DC: danger alert?”

  1. William says:

    I don’t understand why many of you are so scared about DC… The money and the energy you could save with a full-DC system (as you said), makes so that it’s a very good solution!

    It’s true that AC has been the most used system for centuries, but the world has changed and we need to move forward. It is possible to run homes with DC thanks to solar technology and wind power. Most of solar houses use 12V appliances and everything works perfectly well! And it’s not the only example; think about camping lovers… Most of the devices we use today work on 12V, like smartphones or LED bulbs which cost less money than simple light bulbs. Today, nothing prevent ourselves from converting all of our devices to DC. It’s cheaper than full AC systems!

    Of course, it’s still complicated to make a fridge or a washing machine work on DC, but it will eventually happen if we keep moving forward. Anyways, for now, solar panels, batteries and circuit breakers could allow us to come up with a full DC system. Furthermore, since we’re in the USB era we can find power supplies like switches with a USB port included.

    It is clear to me that the AC system is becoming outdated and obsolete at many levels, not to mention the ecological disaster and damage we’re causing to the planet with these billion of cellphone chargers we’re unable to recycle properly.

    So without a doubt I say YES to DC systems!

  2. Roger says:

    If the arcing problem is the only problem against DC power, then DC power wins against AC. Edison already claimed that DC is better then AC. Most properly without knowing why. To start of with, DC es more efficient, no power factor compensation is needed, it can be stored, melting processes for industry are cheaper, lots of electrical phenomena will not happen with DC power. The disadvantage, it can not be transformed which makes it impossible to transfer or transport DC. Once we can store more efficiently DC power, using Hydrogen, then AC power will die away. The arcing problem we have seen in the video can be overcome by faster operating interrupting devices and arc quenching devices.

  3. Ken Crispin says:

    100% for DC current I say as a 5o+ yr Certified Automotive Electrician and a 40+ yr AC Registered Appliance electrician.

    I have seen and worked on both systems in my 50-40 plus years as a tradesman.

    DC is far more efficient and safe, and I consider DC is miles ahead as a safety energy source in my experience of using DC power over AC regarding use of both in our home or mobile environment.

    Sure the arc over is a problem for high voltage DC, no question.

    But capacitors could/should in any event be used to reduce any arc over in switching operation’s.

    This has been used in MOSFET amplifiers for many years where if it wasn’t for trigger transistor capacitors we would destroy all output stage power transistors handling fluctuating switching of DC output power audio power pulses.

    Reduce the DC voltage is as they do in many high voltage DC applications and design appliances to use lower DC voltage of 48vdc to 60vdc accordingly I say.

    We could easily switch to 24vdc to 48vdc motors within fridges to power the compressors or in heating devices.

    We need only use 48v systems which have very little arc over problems in my experience in heavy duty earthmoving machinery I have serviced or fishing boats and motor homes

    Ask any fishing trawler operator about this?

    Sorry I am confident we need to move forward and adopt the lower voltage DC to power our home devices in future and save many lives and property loss, (which would also make Insurance premiums lower with less fire risk.

    Thank you for this opportunity to give input to this forum.

    Ken Crispin NZ.

  4. DC is a great power option. probably the greatest challenge would be in transmission. But with emergence of solar and wind power which might come with dis-integrated units it can be adopted

  5. Jerry says:

    Depends on the application. AC is so much more efficient for long distance transmission and DC is much more efficient for control circuitry. AC and DC can have consequential effects if misused or being serviced by unqualified or inexperienced personnel.

  6. Jacques Peronnet says:

    DKE already worked on this subject. DKE has just published a comprehesive document on this subject.
    This document can be download for free from the DKE website at the following adress.

  7. Ashok R Parikh says:

    DC supply in large quantum for day to day use cannot be maintained by installing the battery banks and back-up AC supply will be required to provide and maintain the dc supply all all probability. Option is to generate dc power directly in the generating station, but I have not heard of any technological advancement made in this direction. The cost of equipment for dc transmission and distribution may also be found prohibitive. With the present day efforts being made to conserve energy, ac power is likely to continue its dominance for a long time to come.

  8. Anil jindas shah says:

    with increasing proportion of the LIGHTING. IT and other sector which work on dc supply , we can have huge saving in power due to the cutting down the energy wastage in converting from AC to DC.

    D C distribution in residential and IT sector can easily be handled by the existing switchgear and control.

  9. Leslie Chin says:

    Household loads are increasingly DC or can be made DC. Solar PV panels generate at DC and electrical storage batteries and hydrogen fuel cells operate at DC so renewable energy systems should be DC for maximum efficiency.

  10. Millions of micro and nano grids, generating its self-sustainable energy on the next future, means less power to be transported through shorter distances to users. It will bring the disruption of the ancient big and long transmission lines structures with more efficient dc distribution systems.

  11. Poonsak says:

    To be known AC and DC values, AC voltage, the average value is 0.632 Vo as we see above sine wave.
    In DC circuit when we are switching(on/off) circuit, it will happen di/dt or we call the change of current in second will happen high value of voltage drop at this switch or at both contact-points. So we can decrease this effect spark by using damping reluctance as we can select in series or parallel circuit resistance and capacitor or/and inductance. Sometime we use semiconductor in reverse connection to be as capacitor.
    And we do use contact less switching by using semiconductor is more safe in operation.
    In Electrical Engineering Laboratory class we had done as your demonstrate and we tested with semiconductor.

  12. With the current progress of DC application (power and electronics), it is in my opinion that DC should be the winner against AC. Transmitting bulk power for long distances even favors the use of DC nowadays instead of the traditional AC.

  13. Leslie Chin says:

    The DC micro grid should be considered for remote isolated communities e.g. single cottages, small villages, islands, northern indigenous communities with their own power sources – hydro-electric generator, solar PV panels, wind or biomass. The system will require energy storage viz. batteries, hydrogen electrolyser/fuel cell or hydraulic pumped storage

  14. sontosh says:

    In my point of view DC is better than AC as the modern world is running on electronics as they consume less amount of power. if one’s all appliances are running with dc then he may use solar panels so that the generating and transmission cost is eliminated. if transmission is required their also the dc transmission is better than ac as the losses less in dc transmission while comparing with ac transmission line .Their will no worry about frequency variations and also power factor variations

  15. KOSHY THOMAS says:

    AC and DC both have their advantages and disadvantages. DC is suitable for transmission for long distances; they have less power loss compared to AC in transmitting the same power. However if we want to distribute it effectively it is better to be in AC form. We can step up or step down the AC using transformers, moreover for the working of induction machines, VFDs etc AC is required.

  16. The greatest disadvantage in the use of a dc power is that it cannot be transmitted over a long transmission line for the purpose of supplying large industries, cities, farm, etc… The voltage drop will occur. There has not yet been a way to augment the power lost for the DC power if it should be transmitted at a long distance transmission line. Therefore, if the dc power must replace the existing AC power across the world, let’s consider how much fragments of dc power sources we will be talking about. It may not be impossible, though, but it will cause a shift of technology in the industry of electricity.
    I think the dc power is playing its unique role in the supply of electricity to the world at large. It is used as a control voltage in the production of large AC power in power stations, steady power supply in hospitals, communication sectors, portable power supply for computers and handy electronic devices, etc…
    Let’s compare this scenario to the automobile industry. Man first began by walking from one place to another, then innovation brought about the use of animal such as horse, camel, donkey, etc… Man excelled to the use of machines to travel. We have Moto vehicle, motorbike, bicycle, airplane, boat, ship, etc… All of these have their unique usage in society.
    New Technology comes to augment the existing one, not to get rid of it. In fact, the production of the dc power is not a new technology. It could not be transmitted on a long transmission line without incurring line drop. This is why the use of electromotive force which could easily augment the power loss along with a long transmission line, through the use of transformers in substations, was preferred. AC power became popular and it has been serving the world for ages.
    Technology has improved greatly. Resistors are used to limit the current to a safe value to avoid flashover that may affect associated sophisticated parts in a circuit.

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