Motor wiring's weird term question.

Hi! When it comes to electrical motor connection wiring what does "all voltage" term mean? I found it as an alternative wiring for "star-delta" in the motor
controller's manual (no drawings, no explanations).
Thanks!
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Haven't a clue. Never heard *that* term.
But "Full Voltage" is sometimes used to describe a motor starter. Rather than connect the motor to "reduced voltage" for starting to limit the in-rush, the motor is immediately placed directly across the line.
Is it possible the question was asking about a motor starter circuit and not just the motor??
daestrom
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not
1st of all, thanks for your reply! Yes, it actually is starter circuit wiring issue. I found that it's possible to wire control circuit 480 or 480/277, so the first configuration is aformentioned "all voltage", the second "delta-star", hope I'm not wrong. Thanks once again.
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Bart



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A three phase motor can be started at 'full voltage', but depending on size, supply considerations and such, often a 'reduced voltage' starting is used. One 'reduced voltage' method is to have all six leads (two for each phase) of the motor winding brought out to the controller. If the motor is designed to work as 480V delta, the starter can temporarily connect the six leads of the motor as star. So each winding only sees 277V. After the motor accelerates (as determined by... tach, current level, simple time-delay or other method), the starter 'breaks' the star at the center and connects those three leads to an appropriate phase so the motor is now connected 480V delta. Needless to say, one has to be careful to interlock the star and delta contactors so they don't pick up at the same time (would result in short). And the phase connections have to be correct so the motor doesn't try to reverse direction when switching from star to delta.
Your welcome
daestrom

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wrote:
| A three phase motor can be started at 'full voltage', but depending on size, | supply considerations and such, often a 'reduced voltage' starting is used. | One 'reduced voltage' method is to have all six leads (two for each phase) | of the motor winding brought out to the controller. If the motor is | designed to work as 480V delta, the starter can temporarily connect the six | leads of the motor as star. So each winding only sees 277V. After the | motor accelerates (as determined by... tach, current level, simple | time-delay or other method), the starter 'breaks' the star at the center and | connects those three leads to an appropriate phase so the motor is now | connected 480V delta. Needless to say, one has to be careful to interlock | the star and delta contactors so they don't pick up at the same time (would | result in short). And the phase connections have to be correct so the motor | doesn't try to reverse direction when switching from star to delta.
Wouldn't a 3-pole double-throw contactor be sufficient for that? Since each winding is going to have one wire connected to a phase line, the other would go to the contactor, which in one state connects them all to neutral, and in the other, to the next phase, which will give either a plus 30 or a minus 30 degree phase angle change, depending on which way you go.
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wrote:

size,
used.
phase)
six
and
interlock
(would
motor
each
would
in
30
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> | Phil Howard KA9WGN |

While one could "lashup" a home brew Wye-Delta reduced voltage starter, the
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wrote:
| While one could "lashup" a home brew Wye-Delta reduced voltage starter, the | consequences of the home brew going South, or the liability issues if one | were to injure property/personnel while doing so, are more than most | reasonable people would risk. | | Most commercial Wye Delta starters are interlocked both electrically and | mechanically for obvious reasons, and could also be of the open/closed | transition type.
And what kind of interlocking is less likely to result in a shorted condition than a double throw contactor?
| The links below might be helpful in understanding the theory of Wye Delta | Starters. | | http://www.usmotors.com/products/ProFacts/1-120-7.htm | | http://www.squared.com/us/products/nema.nsf/bce2f96988bd1a338625643a006e3b29 | /32451b329addd9bf85256712005af2f4/$FILE/C_50006-026-01.pdf
Nothing new there. I'm not asking about the theory of wye start; I'm asking about the need for an interlock as a means to prevent a short circuit path between phases.
| I'm sure that Google has many others.
Probably. But I'm not sure there's anything readily findable about what I am asking.
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wrote:

While a large knife switch would work, most often it is done with two, three-pole single-throw contactors. One contactor shorts the three lines from the motor together to form a wye, and the other connects each of the same three lines to the next phase in the rotation. Obviously, if both contactors are closed at the same time, you have a direct line-line short. So both electrical and mechanical interlocks are placed between the two contactors to prevent this.
If you can find a three-pole, double-throw contactor, you could use one. But remember this thing has to shift while under load (possibly higher than rated current for the motor if you shift before up to full speed). I'm sure *somebody* makes such a thing, but the much more common practice I've seen is to use two single-throw contactors.
daestrom
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wrote:
| While a large knife switch would work, most often it is done with two, | three-pole single-throw contactors. One contactor shorts the three lines | from the motor together to form a wye, and the other connects each of the | same three lines to the next phase in the rotation. Obviously, if both | contactors are closed at the same time, you have a direct line-line short. | So both electrical and mechanical interlocks are placed between the two | contactors to prevent this. | | If you can find a three-pole, double-throw contactor, you could use one. | But remember this thing has to shift while under load (possibly higher than | rated current for the motor if you shift before up to full speed). I'm sure | *somebody* makes such a thing, but the much more common practice I've seen | is to use two single-throw contactors.
If single throw contactors can be made with the ability to handle these make-break loads, I'm sure a double throw contactor can, as well.
If a double throw contactor were what engineers wanted to use, I'm sure they'd make more of them. Perhaps the issue is the open transition time.
This reminds me of the issues I see in transfer switches. Most are based on 2 separate switches or breakers plus some kind of mechanical interlock. Maybe some of the industrial versions are plenty good enough, but most of the home versions I have seen are too flimsy to trust them. The one with two arms pivoting on one point where they swing to shut one breaker off if the other is flipped on just seem to shout at me "ready to break". Even the ones that you have to slid back and forth manually look too flimsy. If those were made strong and mounted better, I might feel more comfortable with them. But I need to go with a transfer switch that has common blades or contacts that simply can't be "in two places at once".
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wrote:

Sure, except that I don't think anybody makes a double-throw contactor. It also wouldn't work in a closed transition arrangement. Actually, most wye-delta starters use a 3 pole and a 2-pole contactor, mechanically interlocked.
Wye-delta start is not too common in the US. It can't be used on the popular 9 lead motors. Then too, none of the reduced voltage starters, other than possibly the autotransformer type, really benefit anybody except the utility. One possible exception is when you need a very low starting torque. Reduced-voltage starters are perhaps the most mis-applied and mis-understood pieces of electrical hardware.
Since each

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wrote:
| Sure, except that I don't think anybody makes a double-throw contactor. It | also wouldn't work in a closed transition arrangement. Actually, most | wye-delta starters use a 3 pole and a 2-pole contactor, mechanically | interlocked.
I've seen them. Even wired one up once (single pole for another purpose). And I've even seen them on an elevator controller.
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does "all voltage"

"star-delta" in the motor

It means that the motor can be connected for a wide range of voltages... but certainly NOT 'all voltages'... for instance it surely wouldnt run on 2 volts AC or 9,000 vac either.
It sounds like a public relations term meant to indicated it will run at all usual and common voltages in its target market...such as 220 or 440 3 phase etc.
Phil Scott

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wrote: |
| |> Hi! |> When it comes to electrical motor connection wiring what | does "all voltage" |> term mean? I found it as an alternative wiring for | "star-delta" in the motor |> controller's manual (no drawings, no explanations). | | | It means that the motor can be connected for a wide range of | voltages... but certainly NOT 'all voltages'... for instance | it surely wouldnt run on 2 volts AC or 9,000 vac either. | | It sounds like a public relations term meant to indicated it | will run at all usual and common voltages in its target | market...such as 220 or 440 3 phase etc.
I'll take one that does 110-120, 127-139, 190-208, 220-240, 254-277, 318-346, 380-416, 440-480, and 550-600. :-)
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wrote:

As an aside to the asides already going on in this thread, I will venture a guess at the original poster's question.
You mention that something says "Delta-Star" on the starter, as opposed to "All Voltage". This to me indicates a somewhat poor job of translating some sort of language into "American-English", so they may have misinterpreted the commonly used term "Full Voltage" for "All Voltage" since in some languages, All and Full may be the same word. I say this because were this being done for England, Autralia or some other Brittish-English speaking nation, the translation would have been Direct-On-Line, instead of Full Voltage when referring to starters.
Am I correct that this is a staerter made in, perhapse, an Asian nation? If they were as of yet unfamiliar with marketing in the US, they will make these kinds of mistakes for a while.
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