how many volts are in 6kw

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or in other words, your question is similar to saying: if the area of a rectange is 10, how large is the long side ? there are many answers.

similarly, power (kw) = voltage (volts) x current (amps)
 
Example 6000 watts divided by 25 amps equal 240 volts. You will need to know at least two of the three to figure the third.
 
jwbulldog35 said:
kw to volts
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First of all, Welcome to the Forum, JW.

Don't let these clowns put you off. They're just having fun with the image that 480sparky posted when responding to your first post.

Moderators note; Al is referring to some posts that were removed

Your question is not clear. What are you asking the question about? Is it a test question, or something you're working on? It helps to give the details.
 
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kVA = kilovolts * amps

pf = power factor = cosine of the angle between the current vector and voltage vector

kW = kilovolts * amps * pf

pf = kW / kVA


In other words, we are missing two input values needed to answer your question: the amps and the power factor.
 
mivey said:
kVA = kilovolts * amps

pf = power factor = cosine of the angle between the current vector and voltage vector

kW = kilovolts * amps * pf

pf = kW / kVA


In other words, we are missing two input values needed to answer your question: the amps and the power factor.
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How often do you really know the power factor. Afterall it is determined by the load. I usually omit it but if I feel the need to include it I usually defualt to a .8 PF.
I heard once....and I have no idea how they came up with this. But if you were to Thevinize the grid you would end up with about a .8 PF. I assume that is why most generator, transformer nameplates have a KW rating based on a .8 PF.
 
al hildenbrand said:
Ow! Just thinking of boiling down to the equivalent diagram hurt my head.
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Yeah....I was tuaght how to do it once for simple circuits. I don't even remember where to start anymore. The guy who did it for the grid...I'd like to meet him. I think he stared in the movie "A Beautiful Mind"
 
mikehughes8 said:
How often do you really know the power factor. Afterall it is determined by the load. I usually omit it but if I feel the need to include it I usually defualt to a .8 PF.
I heard once....and I have no idea how they came up with this. But if you were to Thevinize the grid you would end up with about a .8 PF. I assume that is why most generator, transformer nameplates have a KW rating based on a .8 PF.
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If sizing equipment, you should find out. I have seen industrial feeders with a 65% power factor.

My house has two panels, one leg at 79%pf, one at 95% pf, and the other two at 98-99% pf. That will vary, of course, as the loads change.

The 80% pf on a generator is a blanket assumption, but must be validated with some analysis of the type loads being served. You may find you will have to de-rate the generator from the 80% pf rating.

Transformers are rated by kVA or VA, etc.
 
I liked doing Thevinin equivalent diagrams. . . they were satisfying to the part of me that also liked diagramming sentences.

Never really thought about the grid that way until I read your post. The image in my mind just kept opening like a fractal view burrowing smaller and smaller.
 
mivey said:
If sizing equipment, you should find out. I have seen industrial feeders with a 65% power factor.

My house has two panels, one leg at 79%pf, one at 95% pf, and the other two at 98-99% pf. That will vary, of course, as the loads change.

The 80% pf on a generator is a blanket assumption, but must be validated with some analysis of the type loads being served. You may find you will have to de-rate the generator from the 80% pf rating.

Transformers are rated by kVA or VA, etc.
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I agree that in certain circumstances it becomes important. However, in other common application (residential) I think it can be omitted or reasonable assumed to be .8.
It will vary more leading or lagging at times but it most cases the source should be sized to handle the variance.
 
al hildenbrand said:
I liked doing Thevinin equivalent diagrams. . . they were satisfying to the part of me that also liked diagramming sentences.

Never really thought about the grid that way until I read your post. The image in my mind just kept opening like a fractal view burrowing smaller and smaller.
Click to expand...

Come to think of it the information needed to determine the PF for the grid wouldn't be hard to come by. Afterall, all the POCOs know the PF at each of their plants.
 
They are not Thevenizing the grid to get the power factor, they are measuring vars. And I doubt it is any where near 80%. The transmission system will have better var maintenance than that.

A city might be 85% or it might be 95% or who knows what, but they will try to get to the 90's.

There are diminishing returns after you correct much more than the low to mid 90's (i.e. there is a knee on the return graph).

Individual loads that the EC may deal with could be most anything so need to be looked at closely sometimes.
 
mivey said:
They are not Thevenizing the grid to get the power factor, they are measuring vars. And I doubt it is any where near 80%. The transmission system will have better var maintenance than that.

A city might be 85% or it might be 95% or who knows what, but they will try to get to the 90's.

There are diminishing returns after you correct much more than the low to mid 90's (i.e. there is a knee on the return graph).

Individual loads that the EC may deal with could be most anything so need to be looked at closely sometimes.
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Yes, I realize that they are not Thevinizing at the plants. Real Power (KW), Apparent Power (KVA)...and the missing piece to the power triangle KVARs. I actually operate medium voltage plants (sometimes in manual mode). This is fun. As the load changes you get to constantly adjust the balance between your individual units. I actually prefer it to the automatic mode which can get extremely boring.
 
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