The Differences Between AC Power and DC Power and Their Uses

We use both AC and DC current on a daily basis for digital electronics and various power outlets. However, people still don’t know the basic differences between these two, and why we need both.

With that in mind, we’re going to examine some of the key differences between AC and DC, as well as talk about their use in our everyday lives.

Alternating Current vs Direct Current
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Alternating Current (AC)

Alternating Current is nothing more than a periodical change in direction of the flow of charge. Simply put, alternating current is here to describe the flow of the electricity through the conductor. As its name suggests, the flow of the current is periodically changed, reserving the voltage level along with it. Alternating Current is supplied to households and office buildings and can be converted to direct current if needed.

AC Generation

Can you generate an Alternating Current? Of course, you can. The most popular device for generating AC is called an alternator. Inside the alternator is a magnetic field as well as a loop of wire which is spun inside, used for the current induction. To produce the current, this wire needs to have some kind of rotation, which can be produced by flowing water, steam turbine, or wind turbine. During the spinning process, the wire periodically changes its magnetic polarity which makes both current and the voltage alternate.

AC Waveforms

When it comes to the waveforms, an Alternating Current is vastly different from a Direct Current. As you’ve probably guessed, AC waveforms come in a form of a sine wave. This can be seen easily if we connect the oscilloscope to a circuit with the Alternating Current. Here, we can see a couple of waveforms in which the sine wave is the most common. In most cases, an Alternating Current that you use in your home has the exact same sine wave. This indicates that the amplitude of the current flow changes over time, which is exactly what an Alternating Current is.

Since we mentioned different types of waveforms, it’s important to mention the square wave. The square wave is often used in switching and digital electronics for testing purposes. This type of wave indicates that the amplitude stays the same for a period of time, before dropping to a negative value and stays there for the same period of time. The process repeats during the operation.

Finally, we have a triangle wave, which is a bit less common. It’s mainly used for testing amplifiers and other linear electronics.

AC Application

As we mentioned earlier, AC is used in our homes and offices. The main benefit of Alternating Current is that it can be easily generated and transported across long distances thus being the number one choice for the aforementioned purpose. Just imagine having to supply a whole city or a part of the city using a single power plant. AC makes it possible – it’s fast and it’s easily generated. On top of that, power plants can use transformers to convert to/from high voltages if needed. The higher the voltage is, the lower the current, producing less heat in the power line.

Many household appliances such as refrigerators and dishwashers also use AC. AC is able to power electric motors which convert this electrical energy into mechanical energy (rotation, translation, torque, etc).

Direct Current (DC)

Direct Current is much easier to grasp since it’s a completely different term from alternating current. While alternating current is going back and forth, direct current provides a constant current in a single direction. The most common example of direct current is a battery in your flashlight or a smartphone, as well as a PSU (Power Supply Unit) in your PC.

DC Generation

DC can be generated in numerous ways. The most common component used is called the rectifier. A rectifier is exactly what it sounds like. Just imagine the sine wave that needs to be rectified or straightened to look like a waveform of the Direct Current. It has electronic or electromechanical elements that let the current flow in one direction. Alternatively, a typical AC generator with commutator can also produce direct current, as well as batteries that produce DC due to chemical reactions inside them.

DC Waveform

Direct Current has only one waveform consisting of a straight horizontal line. This line represents the change (or the lack of change) of voltage over time. In practice, the intensity of the voltage and the current may change but the direction of the flow stays the same. Some DC sources can’t produce this kind of plot all the time, with the typical example being batteries. Over time, they lose their power and the voltage will start dropping at some point, producing a different plot. For the most time, we can assume that the plot looks exactly as we described it – a straight horizontal line that shows constant voltage.

DC Applications

The direct current is used by small electronics such as smartphones, flashlights, and computers. That’s why you need a special power supply in your computer – for converting AC to DC. Other typical applications include TVs, as well as new-generation electric vehicles since they use rechargeable batteries as power supplies.

Conclusion

Both AC and DC have their own purposes and you can’t say that one is better than another. While AC is suited for our households due to its ease of generation and distribution, DC is the only way of powering battery-based electronics and electric cars. Despite the huge popularity and implementation of Alternating Current, most of the electronics we use to take advantage of Direct Current, meaning that we need both of them equally.

Creating a Runtime File and Downloading to a Panelview Plus 7

This is a step-by-step tutorial on how to create a runtime file using Rockwell Automation’s Factory Talk View Studio Machine Edition as well as how to download that runtime file to an Allen Bradley Panelview Plus 7.

1. Open Factorytalk View Studio Machine Edition on your PC.

Factorytalk View Studio Machine Edition
Figure 1: Factorytalk View Studio Machine Edition

2. Open the application you would like to download to the HMI screen.

Open Application to Download
Figure 2: Open Application to Download

3. When your project loads into Factory Talk ME, all of the screens should be loaded into the explorer on the left side of your screen. Now we need to convert the project file into a runtime file to be able to download to the HMI. To do this we will need to convert the file.

Converting Project File
Figure 3: Converting Project File

4. Go to Application and click Create Runtime Application. This will convert the program into a .mer file that can be downloaded to the HMI.

Create Runtime Application
Figure 4: Create Runtime Application

5. Now we need to name the runtime file that we will be using as well as select which version firmware you want to download to the HMI. Selecting the correct version will allow the program to be downloaded to the HMI. The runtime project you create and the firmware version will need to match on the HMI we are downloading to. The menu will look like below.

Naming Runtime File
Figure 5: Naming Runtime File

6. Select the application you would like to create the runtime file for and click Save.

Save Runtime File
Figure 6: Save Runtime File

7. The runtime file will start to compile. It will take up to a minute for this to complete depending on the size of the program. When it is finished, the home screen will reappear.

Compiling File
Figure 7: Compiling File

8. Now it’s time to download the project to the HMI. To download the project, go to TOOLS, then click Transfer Utility.

Transfer Utility
Figure 8: Transfer Utility

9. This is the transfer utility to download the runtime file to the HMI. Make sure your project is in the source file location. If not, select it from the menu by clicking this button: Button

Transfer Utility
Figure 9: Transfer Utility

10. Highlight the correct PV Plus 7 and make sure the IP address you are downloading to is correct.

11. It is a good practice to replace communications every time you download a new runtime file. It’s easy to download the runtime to the wrong HMI if there are many on the network. If the communications haven’t been set up in RSLinks Enterprise, see the communication setup instructions.

12. Click the download button to get a downloading popup window. On the HMI screen, it should flash to black and restart using the new HMI runtime file. If everything is communicating you should see information on the screen that has been programmed into communication.

Downloading
Figure 10: Downloading

13. The default screen on the PV7 HMI will be the main screen. If there is data on that screen in the form of numbers from the PLC, you know everything is communicating correctly.

Default screen
Figure 11: Default screen

14. If there are asterisks (***) in the data fields on the HMI the first thing to check would be the RSLinks Enterprise settings in the HMI project.  See the setting up communication section for more information on this.

Figure 12
Figure 12: Motor screen

This is the end of the tutorial. For more information or to purchase any of the products in this tutorial please visit our homepage here.

Tech Predictions for 2018 That Came True

2018 was an exciting year in the realm of technological advancements, surpassing even the most expertly stated expectations. In October 2017, international business consulting firm Gartner published their predictions for the top strategic technology trends in 2018. A year later, in October 2018, Forbes Technology Council convened a panel of experts to offer their take on the most disruptive technology breakthroughs of 2018. A comparison of Gartner’s forecast to the Council’s retrospective provides clues for what may be in store in 2019. If trends hold, it could be an even more explosive year.

Gartner’s Predictions for 2018

Gartner is a research and advisory company that operates in 100 countries and serves 15,000 client organizations across the globe. Based on their interactions with these clients, Gartner generated the insights which informed their Top 10 Strategic Technology Trends for 2018, a report they released in October of 2017. Making sense of a surging technological landscape that continues to bloom so aggressively can be a challenge, but Gartner categorized the breakthroughs in a tidy fashion, calling the “entwining of people, devices, content, and services” by the loaded term “intelligent digital mesh”, which breaks down as:

  • Intelligent: Systems are increasingly incorporating artificial intelligence (AI)
  • Digital: The line between the virtual and real worlds is blurring
  • Mesh: People, business, devices, content, and services are becoming more interconnected

Using the framework of the intelligent digital mesh, Gartner made their predictions for 2018:

  1. General interest in building business solutions that harness the power of AI would continue to increase steadily through 2018 and even on to 2025.
  2. Existing software applications would incorporate AI to add business value and provide invaluable data to fuel augmented analytics, and an AI foundation would be used for new app development.
  3. Intelligent things, which use AI and machine learning to interact with humans and the environment, would begin to collaborate with one another in swarms.
  4. Digital twins, which are digital representations of real-world objects or systems, would be built using information gathered via the Internet of Things (IoT), and assist with asset management and product improvement.
  5. Edge computing, architecture which places more processing and delivery power closer to input sources, would be implemented by more enterprises in order to address challenges with connectivity, latency, and bandwidth.
  6. Conversational platforms, which receive human input and return the desired outcome by executing complex actions autonomously, would become more sophisticated and less rigid.
  7. Based on observations of Apple and Google, augmented reality (AR) and mixed reality (MR) would be the subject of intense battles in the smartphone landscape.
  8. Though cautionary in their tone, Gartner predicted that exploration of blockchain would extend beyond the financial industry and into realms like government, healthcare, and supply chain.
  9. Increased demand for situational awareness in digital business strategies, for the sake of swiftly capitalizing on digital business events, would push the capabilities of AI, the IoT, and other technologies.
  10. Privacy and security would need to become more people-centric, with software developers needing to take more responsibility for using security measures. Gartner introduced an approach, continuous adaptive risk and trust assessment (CARTA), in 2017, and continued to encourage adoption in 2018.
Image: Gartner
Image: Gartner

Given these research-based predictions, it is interesting to learn what a reputable panel of technology experts identified as the biggest technological breakthroughs of 2018. Comparing their list with Gartner’s provides validation and some insight into what the future may hold.

Forbes Technology Council’s Nine Disruptive Tech Breakthroughs

Comprised of Chief Information Officers, Chief Technology Officers, and executives from large corporations based in North America, the Forbes Technology Council is an invitation-only organization that facilitates the coalescence and distribution of tech industry expertise. In October of 2018, the group convened to name and describe Nine Disruptive Tech Breakthroughs in 2018:

  1. Low-code and no-code application development capabilities broke down barriers to entry into the custom software development space, making it possible for an average person to create and deploy applications. This plays into Gartner’s predictions regarding AI’s influence on app creation and function.
  2. With the enactment of the General Data Protection Regulation (GDPR) in the European Union, as well as the rollback of Net Neutrality in the United States, there were significant shifts in governmental oversight of consumer data. In addition, large corporations like Google, Apple, and Facebook were forced to respond to heightened consumer awareness of data and privacy issues. While the Forbes panel does not specifically cite CARTA, they are in alignment with Gartner’s forecast.
  3. Use of convenient, sophisticated, voice-based applications like Amazon Echo and Google Assistant rose dramatically, just at Gartner anticipated when identifying conversational platforms as a trend to watch.
  4. Blockchain is hailed as “game-changing” in its versatility and ability to speed up transaction processes. The Forbes panel even predicts that its decentralized nature could likely eliminate middle actors from transactions. While Gartner’s excitement about blockchain is decidedly more measured, they are in agreement with the Technology Council.
  5. Healthcare information technology (IT) began a new wave of cross-sector collaboration, to bring their practices up to generally accepted standards. Gartner did not mention healthcare specifically in their predictions, but one can infer that technologies they did mention, such as edge computing, digital twins, and security, are very likely rolled into this breakthrough.
  6. Clearly the star of the show in 2018, AI is lauded by the Forbes group for enabling predictive analytics derived from massive amounts of data. Technology Council member Laurent Simoneau points out, “There’s data about what customers have browsed, bought and used, about the content they’ve read, documents they’ve downloaded and the results they’ve achieved.” Essentially, Gartner’s prediction about digital business events was manifest in 2018.
  7. While Gartner called out edge computing as a potential remedy for issues with bandwidth, latency, and connectivity, the Technology Council highlighted the introduction of 5G technology as a disruptor in the 2018 technology scene. Thanks to the enormous boost in speeds, new applications and avenues for connection are being introduced.
  8. Augmented reality made possible by smarter, more situationally aware devices is leaping forward. Both the Forbes team and Gartner recognized the hotness of the AR trend, with Luke Wallace pointing out, “Now that multiple users (even across platforms) can interact and look at the same augmented reality from their own perspective, it makes the experience so much more valuable and fun.”
  9. Real-time foreign language translation, specifically Google’s Babel-Fish earbuds, is facilitating understanding like never before. Though Gartner did not include such a technology in their list of 2018 strategic technology trends, it is safe to assume that enabling technologies were on their radar.

Gartner’s Top 10 Strategic Technology Trends for 2019

With predictions so on the mark, at least relative to the Forbes Technology Council’s list, it is no surprise Gartner’s forecast for 2019 follows a near-identical script. In their Top 10 Strategic Technology Trends for 2019 report, the consulting firm builds upon its intelligent digital mesh framework and moves the milestones on logical trajectories. For example, Intelligent Things in 2018 evolves into Autonomous Things in 2019.

 

Image: Gartner
Image: Gartner

It is clear that the breakthroughs achieved in 2018 were not encapsulated within the year, and some technologies will unfold at quicker paces than others. Maintaining awareness of the timeline and the context for each tech trend is key to anticipating the next disruption. Regardless of your expertise, be it derived from peer-reviewed research or based on personal experience, one thing is for certain: These are exciting times.