Why Do We Use AC or DC Power?

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In today’s video we are going to discuss the two differents types of power we use every day in all sorts of electrical applications: AC power and DC power.  More specifically, we want to talk about why we use AC or DC power in various applications.  In many cases, you may know you need DC power for your specific scenario, or maybe a transformer to change to the voltage needed for your situation, but why are these changes necessary?  Our hope is that by the end of this video, you have a better understanding of why we use components such as: Transformers, power supplies and power converters in so many of our electrical systems today.

Let’s first discuss the basic differences between AC power and DC power.  Electrical current is the flow of charged particles, or specifically in the case of AC and DC, the flow of electrons.  The main difference between AC and DC power is the actual direction of the electron flow.  DC power sees current moving in one direction and is constant.  To better illustrate the constant nature of DC power,you can look at a graph, DC power will look like a straight line moving from left to right.  AC power on the other hand, changes constantly over time.  In this case, current can can flow in both a positive and negative direction.  On a graph, this current flow looks like a sine wave, going up and down, alternating between a positive and negative flow.  Hence the name Alternating Current.  (Example)

So let’s talk more about AC power and why it is used where it is. When power is generated, in almost all cases, it is generated in the form of AC power. Which is one of the reasons why it has become the more predominant form of power used today.  We have the ability to transmit AC power at very high voltages and lower current levels over long distances  This make it easy to take power that is being generated and send it to locations all over the world.  The voltage levels generated with AC power can be easily changed up or down with the help of a transformer (which is a relatively inexpensive and mechanically simple device). https://www.rspsupply.com/c-3732-transformers.aspx

With the ability to change the voltage levels, we can easily scale the amount of power that is needed in different applications.  For example… The power that is provided to our homes comes in the form of AC power.  Typically between 120 and 240 volts.  Devices that can be used with AC power are not affected by the alternating characteristics of this form of power.  Some common examples are: lightbulbs, many types of heating elements, AC motors, etc.  However, some electrical devices are affected by this alternating current, in which case, a different type of power is needed.  DC power.

Because DC power is more difficult to generate, and because it is more difficult and expensive to convert AC power to DC power, it is not commonly used as the main power source for most applications.  However, it is widely used in many different scenarios and converted when necessary. It is common to see DC power being used in more complex electrical circuits.  More specifically, DC power will be used when electrical components require some type of microchip.. or processor.

The nature of these microchips do not allow them to  function with current that alternates back and forth from positive to negative.  They need a constant, steady voltage source that DC power can provide. This is why the more “intelligent” electrical equipment that you have is typically being supplied with DC power.  Even in devices such as computers and Televisions, that are being supplied AC power... they are actually using DC power.  These devices convert AC power to DC for the components in that device that cannot operate with AC power.  DC power is also used in many other applications such as charging batteries (which supply DC power), many lower voltage applications and DC motors.  So while more difficult to generate or convert, DC power is widely used, especially in more complex electrical circuitry... where it is an absolute necessity.

As you will commonly see,  both forms of power will be used simultaneously in many different applications.  For example, in an industrial control cabinet, you will typically see AC power being supplied, which will power some of the components within the panel… specifically components that are not affected by the alternating characteristics of AC power.  You will then see that AC power being converted to DC power for the devices that are more complex and have some type of microchip or processor that requires DC power function properly.

YouTube url:	https://www.youtube.com/watch?v=pruyEzfneJI
Created:	15. 10. 2018 22:43:54

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Why Do We Use AC or DC Power?