Hi, a 3 phase short circuit current is bit weird to me. How a three current 120 degree apart makes up a high current ? They add up? Can you tell me what happens when 3 phase is shorted (bolted). İt is easy to imagine what happens with phase-neutral but 3 phase is confusing...
Three phase shortcircuit current
- Thread starter electrics
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ptonsparky
Tom
- Occupation
- EC - retired
Do you have a problem with a 3 phase 1000 hp motor drawing more than a 10 hp? Just think of it that way. It's just a bigger load and if the equipment is not designed to handle it, things break.
- Location
- Massachusetts
I think the problem is that we are not really understanding the question.
If you have a difference of potential between any two conductors and connect them with low impedance there will be a fault regardless if they are 180, 120 or 60 degrees apart.
dear İwire I think you dont read what I am asking. Here two phase or phase neutral is not point (As I mentioned in the first message) but three phase is. A point at which three phase is connected and what happens ? İmagine that three phase each one is at different potential and you connect them. Doesnt it sound weird?
zog
Senior Member
- Location
- Charlotte, NC
Look at a 3 phase sine wave, that will show you the potential differences from phase to phase. There are times when there is none, there are times it is about double the "phase to phase (RMS) voltage"
Now take that potential and divide it by the resistance of the fault, which can be very low, milliohms in some cases, and you get your fault current.
Now take that potential and divide it by the resistance of the fault, which can be very low, milliohms in some cases, and you get your fault current.
so where do we look at? There is a point at which three different phase voltage is joint. But you say as if we must look at a point which connects two phase. I am asking how can be that three voltage is connected and what happens when done so? I can understand two phase since it means a "difference" and things get easier. But with three voltage I cant see the" difference" ."For which one and which difference" is weird to me..
- Location
- Massachusetts
dear electrics, I have made every effort to understand the words you have typed ......
- Location
- Massachusetts
Yes you are right dear İwire, I think even to ask such a question is difficult since it was not complicated but just confusing matter.
I was confused by the shorting of three phase and I got that it was a simple circuit and not a big deal. I was confused in fact by the impossible situation in which two different voltage is shorted by a "zero" impedance. İn fact there is no such a short circuit in the nature isnt it? now I am okey
I was confused by the shorting of three phase and I got that it was a simple circuit and not a big deal. I was confused in fact by the impossible situation in which two different voltage is shorted by a "zero" impedance. İn fact there is no such a short circuit in the nature isnt it? now I am okey
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