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Could you possible use whole words so what you're saying is understandable? Text speak is not appropriate for online forums. Are you saying you have 2 230v lines with 120 degree phase shift? Not sure about the power system where you are but that seems unusual.
The simplest way to do that is to use a 240V single phase motor to drive a second motor wired for three phase, and use the taps on the three phase motor as the power supply.
On a side note, aren't most 240V systems split phase not single? It's important for grounding reasons.
Is not the 110v considered split phase, but the 220v is single? Even most literature I've read calls 110v center tapped single phase.
"To avoid confusion with split-phase motor start applications, it is appropriate to call this power distribution system a 3-wire, single-phase, mid-point neutral system."
Is not the 110v considered split phase, but the 220v is single? Even most literature I've read calls 110v center tapped single phase.
U r right.Thats i mean to say.Consider a 3 phase supply having 3 wires each with 230 volts and the 4rth wire is at ground potential.Each of the three wires have voltage with phase difference of 120 degree.What will be the potential difference across any two live wires?.And prove ur answer using mathematics,plz
110V CAN be 1 half of a split phase circuit, it is not in fact split phase itself as one wire is a grounded neutral. 'split phase' is where one line is 110V's and the second line is ALSO 110V's but 180 degrees out of phase, obviously a third wire needs to be run for ground unless the whole thing is completely isolated, but as tcmtech and others scolded me about in a thread last week it's not in fact considered polyphase AC power, hence the term split phase.
I find the terminology a needless run around as you CAN have 110V single phase power. Depends entirely on the pole transformer and it's a whole lot of technicalities about what you call it.
There is the ability to have a true 2 phase power system that's not split phase but I never got a really good description of one. Basically to be called polyphase one of the line voltages must specifically come first, IE guaranteeing the rotor direction of a polyphase motor will always be constant giving connection to the proper phases.
I find the terminology a needless run around as you CAN have 110V single phase power. Depends entirely on the pole transformer and it's a whole lot of technicalities about what you call it.
When you use it every day its not a needless run a round but a very important aspect of being properly understood and having the right device used in the correct application.
How would you like to have a prostate exam and your doctor says that endoscope and scalpel are just needless medical terminology because they are both medical devices used in medical application stuff so whats the difference if you mix them up in actual usage?
If you thought the endoscope was uncomfortable wait until he grabs the scalpel and redoes your exam!
hehe, good point tcmtech. I just get grumpy when something that should be simple gets bogged down in technicalities.
I still consider in my deepest heart that split phase is a polyphase system =) Just from the word useage. I'll burry that deep down right there with my thoughts on Ohm's Law and electron vice conventional current flow =) I'll stop the rant now cause I already let lose on that one, even though technically I was wrong (except for the conventional current flow which is just a matter of opinion)
The simplest way to think of the phase relation is to look at the zero crossing points of the waveforms of any or all lines in reference to each other. If they all cross the zero point in the waveform at the same time its single phase regardless of how many lines or voltages are present.
If they cross at different times in relation to one or another it is a multi phase system. From there you can extract the phase angles, number of phases, and other stuff.
tcmtech: In the case of a split phase system there is still a phase angle, and a number of phases in relation to the center tap. It just can't be determined by zero crossing... in theory. That's a fine distinction. Basically it means it's a polyphase system if the phase angle is ANYTHING other than exactly 180 degrees. Where do you draw the line? On a split phase system an unbalanced load.. like a fridge on one leg and nothing but light bulbs on another would technically qualify as being polyphase because of the lead/lag from the loads... Three phase systems typically have 120 degrees phase difference. So you understand my irritation with the technicalities. Give me a scope and a split phase system and I'll show you a lead lag that shows it's polyphase vs neutral/ground.
Typically you just reference off of the power source as if it had no load on it.
If its 180 +- some degrees its single phase. If its 120 +- its three phase. If its 90 +- its two phase.
As you already know in reality things always have those annoying imperfections and slight variations from the ideally perfect conditions that always go with them.
The slight phase drifts are in the same category as the real sine waves that the electrical systems we use have. We call them sine waves but anyone who has ever ran them on an O- scope on their power lines knows they tend to not be so symmetrical and perfect as their name implies.
They are closer to a sine wave than square or triangle waves but not a mathematically perfect sine wave by any stretch of the imagination!
I run unmodified three phase motors off of single phase. That doesn't make them single phase motors or my power system a three phase system either. In the circuits between them I am just twisting the phase relations where needed to make each part work together! Both follow their true designed nature but with that bit of twisting and bending in the middle of course!
I know tcmtech, thats' where my grumpiness comes from.
120 degree is polyphase 180 isn't, and there's no boundary listed. For a technicality it's lacking in technicalities!
It's kind of like saying you can't use a polyphase motor on a single phase system, but if you use a capacitor to phase shift it enough for the motor to start for even one rotation it WILL continue to run, albiet with pretty heavily reduced torque. Some really slap dash single to poly phase systems use this method to extract a third phase from a power supply for starting of lower power three phase systems.
The boundries are in fact very very grey, and not so black and white as I see in papers everywhere.
Industry standardization on the power side of electrical systems has made it so its not really much of an issue. It is a three phase power source or it is not. What gets done with or to it afterwords is not relative to the base terminology used to name it.
Its like saying its a AC or its a DC power source. Once the AC goes through the rectification process its now not AC any more. It still has the same sine wave shapes and amplitudes and if you set a O-scope up to look at it it still has the 0 to peak sine half's but that doesn't make it AC!
Converting single phase to poly phase by some method makes the end result polyphase but not the source. What ever accounts for the mid point conversion is where the terminology gets split at.
On one side of the rectifiers its AC on the other side its DC. On one side of the conversion process is single phase on the other side its not any more.
The simplest way to do that is to use a 240V single phase motor to drive a second motor wired for three phase,
and use the taps on the three phase motor as the power supply.
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