Added: 4 years ago
From: blackrobe28
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  • Excellent video. See my channel electric motor new design.

  • So, if you use 3 phases instead of 1. You get a DC like power?

  • @sybyabraham NO you do not

  • so instead of having a voltage that fluctuates at say 50hz,you have three voltages that fluctuate at slightly different cycle times so that the voltage remains more constant? trying to understand it in lamens terms!

  • @markzilla6969 No you have 3 different phases that fluctuate which is why you have to have at least 3 wires to provide 3 phase service

  • What simulator app are you using?

  • hola todos me podrias ayudar he conectado un motor de 1hp a un generador de imanes de neodimio con bobinas en serie que alcanzan los 123vca por fase pero al conectarle un motor de 1/2hp n se meve y si hay los 7 amperios no se el poque le pongo una retencia de 20 homs y la calineta a solo 3 minutos a 5.6 amperios me tiene desconsertado peued ser por el capacitor o no entiendo el poque lo nesecito para engancharlos motor y generdor mi correo es ilumina 33@hotmail.com

  • damn i landed in nerd-land....

  • wow that was really entertaining!

  • A little calculus can go a long way...

  • Phase separation 120 degrees

    Wye - line current = phase current

    Delta - line current is > than phase current by a factor of 1.732

  • what happens when it hits 88mph?

  • Scary face could have popped up, yelling "LEEEEEROOOOOY JEEEENKIINNNNSS!"

    XD

  • Poor and incorrect illustration.

  • any 1 help me here dont know anything about electrics ive just got a garage in my back yard would it be possible to get 3 phase put in my house or the garage so i can get panel saw in there or is it not allowed ?

  • @Steverywak No, the electrical authority in wherever youlive probably wouldnt allow 3 phase, it's almost entirely used for commercial and industrial applications...but you could ask them, worse they can say is no, but even if they did say yes, they would charge you a fortune because they would have to run new lines from the transformer. It would be alot of work for them.

  • 230kV Vacrupter switch operation, attempting to break load from a very long transmission line -and you know what that means...result is not very good

  • thanks a lot all of you for your comments and explanations!!!!!!!!!!!!!!!! grazieeeee

  • That is a flux capacitor on the right.

  • Dammit, I just got an internship involving all this stuff and I can't remember a damn thing from power class. If I remember correctly the center of the wye is neutral, same on the load. In the wye config all line currents are equal, and phase currents are different right? For delta the phase currents are the same and the line currents are different?

  • Yep,

    Center of the WYE creates a neutral point since all three currents and voltages balance each other out since they are 120 degrees apart in phase, (you can try it out on a calculator capable of complex numbers, add 1 angle 120+ 1 angle 240+ 1 angle 360 and you should get zero. This is the neutral.

  • To add on, there are two possible single phase voltages in a WYE system. The first is connecting a device Phase to Neutral. This gives the lower of the two voltages. For a typical business in the US, this voltage is either 277V or 120V. The second type of single phase voltage is connecting a device phase to phase. This produces a voltage that is the square root of three times the phase to neutral voltage, or 480V or 277V (277*sqrt(3)=480V).

  • Close. You are correct that the phase-to-phase voltage is sqrt(3) times the phase-to-neutral voltage. But the common US commercial 3-phase delivery voltages are 277/480V and 120/208V. The transformers to produce 120/208 usually have 4:1 windings and are delta connected on the primary and wye on the secondary.

    Commercial fluorescent lighting is usually 277V so it can be connected phase-to-neutral without an in-building transformer.

  • I meant the phase to phase voltages in the US are 480V and 208V. So, the phase to neutral voltages in the US are 277V and 120V. When you write 480Y/277 you are saying "phase to phase is 480 and phase to neutral is 277". The 480Y/277 and 208Y/120 are two different systems. Each system is derived using a transformer.

  • In Star (WHE) the line current = the phase current on a balanced load I.E a motor, On a motor that is connected in DELTA the Line Currents and Phase Currents are still also equal however the line currents are not the same as the phase currents as the phase Loads are connected across two diffrents phases so the current value is that of a combination of line currents and is also why the voltage is higher than a WHE setup.

  • in other words in a WHE setup (because at the star point the instantaneous values of Voltage add up to equal 0 volts) Line Current = Phase Current, and Line Voltage = Squareroot of 3 X Phase Voltage. In A Delta Setup its the other way Around, LINE VOLTAGE = PHASE VOLTAGE, AND LINE CURRENT = SQUARE ROOT 3 X Phase Current. the reason for no neutral on a WHE or DELTA Connected motor is because the 3 loads are equal and balanced the instantaneous value of current adds up to 0 and cancels out.

  • on a motor connected in WHE or DELTA Normally (if not faulty or broken etc) the Instantaneous values of Current And Voltage Cancel out. however on unbalanced loads connected to a WHE System the currents on each phase may be out of balance which is why we have neutral conductors however because there is a WHE Star Point this keeps the values of voltage of that of a Single Phase Value unlike when connecting phase to phase setup.

  • so yore are saying that in 3 phase there is 3 hot wires and 1 newtral and ground?

  • (English aint my first langage)...

    Three phases means that theres is three different sinusoidale (courbe), they al start at a different point so there is always one going up while the others are going down, it is just that the hertz ( time per minute you complete a cycle) are so fast that you cant see it pysically. Try to take a picture of your computer screen, you'll understand what I mean.

  • In a three phase Y system, there are 3 phases with 3 wires. You CAN have a neutral wire if you connect to the center point of the Y and run a wire from there. The ground wire is typically also connected to the neutral point of the system, although the ground wire does not normally carry current, it only carries current if there is a problem with the electrical system. Most utilities (not inside buildings, but the lines outside) use 4 wire systems, with the neutral grounded.

  • 3 phase systems always have 3 phase lines plus a safety ground. They may or may not have a neutral. Large 3-phase loads like motors and transformers are usually delta wired without neutrals. Neutrals are mainly for single-phase loads that must have one conductor near ground potential. Single phase loads can also be wired between two phases without needing a neutral, though the voltage will be sqrt(3) greater than phase-to-neutral.

  • The voltages are set via the windings of the supply transformer. e.g. 120/208, 277/480 Volts.

    In case of 3 phase 120 / 208 Volts 60 Hz the phases are 120° apart. You tap 120 Volts between phase and neutral and 208 Volts between two phases.

    In case of 1 phase 120V / 240V as in houses. these are 180° apart with the neutral at the midpoint.

    The peak value is sqrt2 * 120 Volts = 169 Volts.

    3phase is sqrt3 * 120 Volts = 208 Volts.

  • om confused what's these

  • somebody explain this to me, ive been an electrical apprentice for 8 months and i think my boss is too dam retarded to know how it works even tho ive asked him numerous times

  • If we were to look at AC (Alternating Current) from the viewpoint of a device being powered by AC, the current would seem to be reversing itself several times a second.

    If we were to "look" through the same device being given three-phase power we would see the current constantly flowing in one direction. That's because the device would switch phases several times a second to be in sync with a single "flow direction" from all three phases.

  • whats the point?

    Whats the advantage of that?

  • single phase is 120 for example, 3 phase is 240, it doubles if its 3 phase

  • there is more to it then that, i am also an apprentice so i don't fully understand it yet. what i do know is different voltages from 120 up to 600 can be achieved by wiring the phases in different combination's.

    the advantage of using two or three phase power is more amperage can be delivered at higher voltage over lower gauge wires. it is a cost saving technique.

    don't quote me on any of this though, as i said, i am just an apprentice.

  • at least ur an apprentice, im juniour in high school in electrical field.. right now we r doing lots of motor control stuff, so thats what go me into knowing more of 3 phase

  • this statement is wrong...

  • you can still get 120 volts off a 3 phase system, the 3 phase system has no relevence to the voltage as your describing

  • yes i know, for example coils on motor starters, there 240v ones and 120, so yes you can get 120v from 3 phase system

  • - blackrobe28

    "That's because the device would switch phases several times a second to be in sync with a single "flow direction" from all three phases."

    do you know how many times a second? would it switch 60 times a second i.e. 60Hz, or three times a second i.e. 20Hz per phase. and what in the three phase devices does this "switching" exactly? a transformer?

    any help is much appreciated, i am just going through my first term of schooling.

    thx

    R

  • GTMElectric,

    The frequency is unchanged. Think of it in this way... imagine the sinusoidal wave of 120V AC current. It starts at 0, then rises to positive 120, then falls to 0, then falls to negative 120, then rises to 0, etc. Now... take THREE of those waves and arrange them so that there is ALWAYS one that is rising. (Yes its possible.) Now you have the ability to always keep the current moving in one direction and never dropping to 0.

  • @blackrobe28

    How this is useful to know, how it applies, how it even approaches an answer to the original question takes more writing space, time and break down. Breakdown of course has a purpose of simplifying, but often frustrates people in "SEEMING" more complicated.

    A great book that covers this is A.T.P.'s "Electric Motor Controls, for Integrated Systems", 4th Edition.

  • @blackrobe28

    In a generator there are 360deg. From 0 to 180deg are Positive & 181 to 360 are negative degrees.

    3phases R spaced 120deg apart on the rotor.

    While Ph.A is @ 90deg or 90deg above 0 (positive peak), Ph.B is @ 225deg & descending to 270deg (negative peak) & Ph.C is at 315deg ascending toward 0 just after climbing FROM 270deg/negative peak.

    When 1 phase peaks positive, the other 2 are each providing half peak amount negative,if added together give a peak amount negative.

  • @blackrobe28 Hold on, one thing here needs to be made clear.

    What you are describing here is a sinusoidal waveform having an amplitude of 120V (i.e the largest swing from the 0v level in either direction) i.e [120 sin (wt + Θ)] Volts

    The waveform has a peak value (which is the same as the amplitude) of 120V, a peak-to-peak value of 240V (-120V up to +120V), but an RMS value of 84.85V.

    RMS for a sinusoid = [Peak value/sqrt(2)], in this case [120V/sqrt(2)] = 84.85V

    .

  • continued.

    When people quote AC voltage levels, unless otherwise stated, they usually mean the RMS value

    In the USA, 120V AC means 120Volts RMS, which is 169.71Volts peak (aka amplitude) = 339.41Volts peak-to-peak.

    In the UK, 230V AC means 230Volts RMS, which is 325.27Volts peak (aka amplitude) = 650.54Volts peak-to-peak.

    Different ways of expressing the same thing!

  • @blackrobe28 No no no, hold on. 120V AC(or 230V in Europe and else where) refers to RMS(root mean square) voltage. The peak voltage is higher than the RMS voltage by the square root of 2(e.g. 170 V in US, 325 V in Europe) for a sinusoidal power source.

    To determine the average power of a resistive load you would have to integrate the instantaneous power P = V^2/R over at least one cycle and divide by the elapsed time. That integration is done in computing the VRMS, hence PAverage = VRMS^2/R.

  • @blackrobe28 but if you take all 3 phases then while one phase is always rising the other two are falling.

    Why couldnt we use 2 phase for that matter? wouldnt 2 phase lower the omount of stress? one phase is rising, the other is falling... I understand there still gonna be a point where the sin waves intersect and cancel out eachother.. but.. oh wait.. i think i kind of get it now.. or not. crap

  • @ActiveStorage each phase has a separate path/circuit

  • @ActiveStorage 2 phase was used at one time, but its easier to start motors (3 phase motors that is)

  • @blackrobe28 So its an easy way to avoid rectifying. I see.

  • Man you shound not talk such nonsense, go read some old school books and learn the truth, all three phases occur during one cycle but they are 120 degrees apart from each other repeating 60 times a second

  • It's hertz, which is alternating so many times per second.

  • @Etrician55 youll get it in 4th year

  • @Etrician55 There are 3 separate phased that are 120 degrees apart in the rotation of the motor or the generator.

    The 3 phases are not carried on one wire so the ripple does not keep the voltage in each phase from dropping to 0 at the beginning, middle, and end of each cycle.

  • now me understand

  • simple to understand

  • first

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