Alternating Current Explained - Animation

welcome to this video course on power in a data center as it relates the data center acts as we'll illustrate in another video the power that enters a data center is usually three-phase alternating current power which is more commonly referred to as three-phase AC power it's important to understand that alternating current works to be able to appreciate the fact that three-phase power is actually three lines that are 120 degrees apart this concept confuses a lot of people so to have that last sentence make sense let's start with how current moves in single-phase power here in the top picture we have a magnet the North Pole is the positively charged Pole and the South Pole is the negatively charged Pole and next to that magnet we have a copper cable coppers used because it has an electron that's easily moved I'm not going to get into basic chemistry 101 that talks about nucleus and electrons and how they function let me just state at a simple level that it takes very little force to move an electron away from the nucleus and a copper atom that's why copper makes an excellent conductor for electrical power with magnetic forces positives and negatives attract if you have two magnets and hold the positive ends close together and let the magnets go they would push away from each other if you held a positive and a negative close together they would attract each other electrons are negatively charged therefore they're attracted towards the positive part of the magnet and repelled by the negative part of the magnet when we position a magnet close little copper wire copper coil the magnetic force is strong enough to be able to start moving the copper electrons the electron closest to the positive Pole of the magnet wants the edge even closer and the one next to it wants to fill the void that the first one just left and the one after that fills an exploit and a chain reaction starts in the copper wire in this simplified example I'm only showing one end of the conference out of a loop there are millions of these electrons in a piece of copper wire as the electrons move they generate current thicker wire will have more copper which means it will have more electrons generating current if the positively charged part of the magnet is directly next to the copper cable the electrons will be moving towards the magnet at their maximum speed the alternate part is if the negatively charged part of the magnet is directly next to the copper cable the electrons will be moving away from the magnet half their maximum speed now let's take that magnets start rotating it clockwise the magnet is perpendicular to the wire note that both the negative and positive poles of the magnet are at equal distance to the copper wire the attracting power the positive pole is canceled out by the repelling power of the negative Pole this means electrons aren't moving so no current is being generated current is expressed as amperes or amps so the HAMP's being generated here or zero if we further rotate the magnet another 90 degrees we have the South Pole of the magnet next to the wire this negatively charged section of the magnet is now repelling the electrons and they are moving in the opposite direction away from the magnet the force of the electrons going from one copper atom to another either towards a positive charge or away from a negative charges what causes current palter nating current is the current flowing from one direction reaching a peak force decelerating until it stops and then reversing direction until it reaches another peak force at which time it slows down and again stops one complete cycle is from zero to maximum positive back to zero the maximum negative and again back to zero that's pull the Hertz in North America we have 60 Hertz per second and most of the rest of the world uses 50 Hertz per second a lot of people see the pluses and minuses like plus 2.3 amps at - 2.3 amps and they get confused I think that one offsets the other it doesn't the positive and negative numbers are used to show the movement of the current current is caused by the movement of the electrons and it doesn't matter which direction the electrons are moving here's the simple analogy think about leaving your house getting in your car and driving down the block the car starts from zero and accelerates to 30 miles or 30 km/h you know there's a stop sign at the end of the block so you start to slow down eventually stop now let's assume you forgot something at home and decide to back up the same distance you just traveled you accelerate to 30 again and then start to slow down as you near your house until you stop did you just travel zero distance of course not you travel double the length of the block you live on even though you're now back at your starting point you just alternated directions that you traveled in our car example you're moving forwards and backwards but with copper wire the electrons move to positive and away from negative magnetic forces by spinning the magnet because the direction of that movement to go backwards and forwards but calling it backwards affords currently doesn't sound right so we just call it alternating current an ammeter measures the amps are current in line some will show positive and negative values and others long another method of measuring current is the use of digital oscilloscope many charts will show positive and negative numbers to reflect the direction of the current remember plus two point three amps provides the same current strength as minus two point three amps let me repeat this critical statement current is caused by the movement of the electrons and it doesn't matter which directions the electrons are moving while the above examples of spinning a magnet are correct that Niagara Falls in the US generates electricity this way other electrical utilities use the same principle but generate current by spending a copper coil inside of the magnetic field as the coil spins electrons move back and forth the picture shows a simple hand crank but utility companies use an outside power source such as steam from coal or gas fired plants to cause the electrical coil to spin inside of a magnetic field one final note is that since Ben Franklin's experiments with electricity the commonly used statement about current is that it is said to flow in the opposite direction of the electrons

Channel: TechTrainerNJ

Views: 129,921

Rating: 4.661972 out of 5

Keywords: AC current, AC power, data center power, Alternating current, electrical power, electricity

Id: _7u6nh35dJ8

Length: 7min 2sec (422 seconds)

Published: Tue Jan 30 2018