Voltage

Voltage Ratings: 110/115/120, 220/230/240 or 440/460/480

This subject comes up a LOT in this and other forums, so I thought it would be a good idea to make it a "Sticky" that can be found and referred to easily when it comes up. There are two "standards" for voltage in North America depending on which END of the wire you are looking at; "Distribution...
forums.mikeholt.com
 
Your question needs some context. Are those the specs for a replacement motor? The motor itself appears to be dual voltage even though the Hayward VS pump assembly only uses the 230 connection.
 
Alwayslearningelec said:
Why would it list this as 115 & 230v? It says it single phase.

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It has two winding groups that you can opt to either wire in series for 230V, or in parallel for 115V. There's a tap selector on the motor that allows you to chose which winding arrangement you want to use. Motors are usually rated slightly less than the nominal voltage of the grid, because it anticipates some voltage drop. It's still meant to connect to either a nominal 240V or 120V grid respectively.
 
AC\DC said:
I think he thinks single phase would be only 120, not 240 since it’s both and A&B phase and not -“single phase”
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It's mathematically equivalent in the ideal case, to two 120V waveforms that are 180 degrees out of phase.

It just isn't called 2-phase, since that name is already taken by a now-obsolete system that had two phases that were 90 degrees apart from each other, to assist with motor starting. And because split phase isn't produced by generator coils separated by an angular rotation, but rather by center-tapping a single phase transformer's secondary coil.
 
Alwayslearningelec said:
But doesn't 115v wiring mean 1 hot and 240 mean 2 hots?
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Yes. But they aren't separate phases by strict definition. They are separate live conductors that ultimately come from the same phase.

They are mathematically equivalent to two separate phases, but not considered to be two separate phases due to how they are produced in contrast to how 3-phase power is produced.

240V also doesn't necessarily mean 2 hots, since rest-of-world voltages would produce 240V (or something in its immediate neighborhood), from a single phase and neutral, instead of 2 hot conductors.
 
Carultch said:
Yes. But they aren't separate phases by strict definition. They are separate live conductors that ultimately come from the same phase.

They are mathematically equivalent to two separate phases, but not considered to be two separate phases due to how they are produced in contrast to how 3-phase power is produced.

240V also doesn't necessarily mean 2 hots, since rest-of-world voltages would produce 240V (or something in its immediate neighborhood), from a single phase and neutral, instead of 2 hot conductors.
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Geez some of that is a little confusing. So for the case I posted you could wire it to a single pole or two pole breaker?
 
Alwayslearningelec said:
Geez some of that is a little confusing. So for the case I posted you could wire it to a single pole or two pole breaker?
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If you need 1 hot conductor, you wire it to a single pole breaker and the neutral.
If you need 2 hot conductors, you wire it to a 2-pole breaker.

If you have a 120/240V split-phase system as is common to single family and duplex residences, you have the option of either choosing 240V or 120V. Usually the higher voltage is preferred, because it is more efficient to send higher voltages long distance.

If you have a 120/208V system, that is derived from a 3-phase wye grid, as is common for apartments, you would only be able to use the 120V option. That is, unless you can substantiate that it can tolerate 208V. You can damage a motor by running it on an undervoltage.
 
Carultch said:
It's mathematically equivalent in the ideal case, to two 120V waveforms that are 180 degrees out of phase. . . . It just isn't called 2-phase
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This gets to what the definition of a "phase" is.

Without going into all the details of the proper definitions (which I believe I understand intuitively but have not worked out rigorously), the meaning of the word "phase" in the statement "these two voltage waveforms are 120 degrees out of phase" is different from the meaning of the word "phase" in the statement "this multi-wire voltage system is a 3 phase system".

The primary difference is that we apply the first usage of the word "phase" to ordered pairs of conductors, and the ordered pair (N, L1) is 180 degrees out of phase with the ordered pair (L1, N). Whereas in counting the phases in a multi-wire voltage system, we ignore phase offsets of 180 degrees and don't count them as different. So any 2-wire system is single phase.

[There is another difference, in that we call both 3P3W delta and 3P4W wye "3-phase", even though in the wye system you can get 6 different phase offsets between ordered pairs of conductors, even after you ignore 180 degree differences. So in the 3P4W wye system, by convention when we count phase we either require that they all involve N, or none of them involve N, but not both at once.]

Cheers, Wayne
 
They are not 180 degrees out of phase. They are opposite in polarity. In reference to the neutral the two sine waves would appear to be 180 degrees apart, but that is just an illusion.
 
CoolWill said:
They are not 180 degrees out of phase. They are opposite in polarity.
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For the case of a pure sine wave, the usual starting idealization for these discussions, the two notions are equivalent, as sin(theta + 180 deg) = -sin(theta). But you are correct for other cases, e.g. if there is a DC component to the voltage.

Cheers, Wayne
 
It is SINGLE PHASE!

Take an isolated oscilloscope (no ground reference) that is capable of having 250 VAC on its input. Take the scope probe and connect the alligator clip to one hot wire in the home panel, touch the probe tip to the other hot wire You see? ONE SINE WAVE! Single Phase. If two channel scope, put the other scope probe onto the neutral. See? The sine waves overlap, the second channel is just shorter by 1/2 in amplitude. Same phase.

Of course you could also use a Fluke 434 or 435 which is made to do this test, and see, ONE SINGLE SINE WAVE shows. Single Phase.

I see most of you never worked on antique (or just old back then...:ROFLMAO:) radios with a center tapped transformer to feed the 80 or 5Y3 rectifier tube to make DC.
 
infinity said:
Would a single phase 208 volt circuit be two sine waves 120° apart?
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Nope. Between the two conductors is still a single, symmetrical sine wave.

It's 208v instead of 240v because of the timing, but it's still a single wave.

Now, if you're referencing the neutral, then you have 3 conductors, not 2.
 
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