# Electrical safety quiz



## Teetorbilt (Feb 12, 2004)

md, if I remember my reading correctly isn't Tesla's invention of the AC motor the deciding factor in changing Edison's version of powering with DC? I also remember him having something to do with the flourescent tube. Didn't he also illuminate a house wirelessly?

He may have been nuts but he never cut off an ear to prove it. BTW, many of the Tesla coils have yet to be improved on. Many of his experiments with ultra low frequencies are still well harbored within todays government.

A few of his verboten manuscripts are still out there. I know!


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## Sparky Joe (Apr 29, 2006)

Teetorbilt said:


> md, if I remember my reading correctly isn't Tesla's invention of the AC motor the deciding factor in changing Edison's version of powering with DC? I also remember him having something to do with the flourescent tube. Didn't he also illuminate a house wirelessly?
> 
> He may have been nuts but he never cut off an ear to prove it. BTW, many of the Tesla coils have yet to be improved on. Many of his experiments with ultra low frequencies are still well harbored within todays government.
> 
> A few of his verboten manuscripts are still out there. I know!


I would like to obtain a good documentary about Tesla, if one exists, perhaps the History channel?

Keep in mind that inventions attributed to Westinghouse were created by Tesla(he was just the marketer, so to speak)


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## Teetorbilt (Feb 12, 2004)

I have all of Tesla's legal works here. I know where the rest can be found, I have read them.


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## JamesNLA (Jun 2, 2006)

> I would like to obtain a good documentary about Tesla, if one exists, perhaps the History channel?


It's either history channel or TLC.....hmm, maybe discovery.
It covers all the guys and their respective inventions/discoverys. I seem to remember a large portion of the doc was on the argument of who really discovered DC and why AC became the power of choice.

Hint, has to do with oceans!!

It's a good doc and you can buy those shows for like 15 or 20 bucks from their websites.

AND if somebody doesn't start answering these basic electrical theorys, I'm going into the rafters to crack out my books...FROM FIRST SIMESTER:laughing:


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## DAVIS081404 (Oct 20, 2006)

Sparky Joe said:


> In fact just look at Table 430.248 and 430.250;
> 
> single phase, 230 volt, 1 horse = 8 amps (1840 watts)
> 
> ...


 
This is where service factor and efficency rating would come into play. The 746watts is equal to 1 horse power (single pahse or 3 phase). The 1840 watts is just a calculation from the 8 amps muitplied by the 230volts. It doesnt tell us nameplate info. If they could make a motor with a 100% efficency rating it should only consume 746 watts during normal conditions. Of course thats assuming it is running at 1.0HP. Basically 746watts is the same amount of energy as 1 hp in a perfect world.


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## CE1 (Dec 30, 2005)

Sparky Joe said:


> I would like to obtain a good documentary about Tesla, if one exists, perhaps the History channel?
> 
> Keep in mind that inventions attributed to Westinghouse were created by Tesla(he was just the marketer, so to speak)


Joe try this website: http://www.pbs.org/tesla/index.html


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## Sparky Joe (Apr 29, 2006)

DAVIS081404 said:


> This is where service factor and efficency rating would come into play. The 746watts is equal to 1 horse power (single pahse or 3 phase). The 1840 watts is just a calculation from the 8 amps muitplied by the 230volts. It doesnt tell us nameplate info. If they could make a motor with a 100% efficency rating it should only consume 746 watts during normal conditions. Of course thats assuming it is running at 1.0HP. Basically 746watts is the same amount of energy as 1 hp in a perfect world.


So you're saying a single phase 1 horse motor is only 40% efficient?

I highly doubt it, I'd guess more in the high 90's


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## DAVIS081404 (Oct 20, 2006)

Sparky Joe said:


> So you're saying a single phase 1 horse motor is only 40% efficient?
> 
> I highly doubt it, I'd guess more in the high 90's


 
I dont think I can say that a 1 HP motor is X % efficient. There are many differant motors with numerous differant ratings. I doubt the motor they are referancing is 40% (possible but not likely). However since they didnt list any information that is just a guess. We also dont know the service factor of the motor, which gives us a differant variable altogether. Service Factor (1.65 - the motor is rated to safely operate at 1.65hp). A motor operating at 90% efficiency would be a very efficient motor. Id be interested to see what numbers they used to come to there conclusion in the book.


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## Sparky Joe (Apr 29, 2006)

DAVIS081404 said:


> I dont think I can say that a 1 HP motor is X % efficient. There are many differant motors with numerous differant ratings. I doubt the motor they are referancing is 40% (possible but not likely). However since they didnt list any information that is just a guess. We also dont know the service factor of the motor, which gives us a differant variable altogether. Service Factor (1.65 - the motor is rated to safely operate at 1.65hp). A motor operating at 90% efficiency would be a very efficient motor. Id be interested to see what numbers they used to come to there conclusion in the book.


So while i dig around through my books (or perhaps do other things), explain to me why then we have 3 phase power if there is no gain from it? Why is the entire world is line to neutral loads, or even single phase 480(since I know your answer would be "wire size" to the previous question). I mean why is there such a thing as 3 phase?

After you answer that I'll dig up my refferences and show you what I am talking about.

Keep in mind that every 3 phase formula is different from the single phase formula to find the same thing. Every 3 phase formula includes the square root of three, aka x 1.73.

Another hint; keep in mind with 3 phase, voltage is never at 'zero'. On a sine wave, with motors volts and amps are always slightly out of phase, there are times(a lot of times, with single phase always crossing zero) where no watts are produced, i.e. amps x 0volts = 0watts or vise versa. Even if 100% power factor were possible this would still hold true.


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## Sparky Joe (Apr 29, 2006)

On another note; I believe it was Tesla that said 1 horse is 746 watts, because of his partner "Westinghouse" was a train builder that determined a horse could lift 10 pounds 10 feet in one second(or something like that), simply so he had a way to rate his trains. And Tesla determined how many watts it took a motor to do the same thing.

Again don't quote me on all the facts, it's just something along those lines.

edit; 1 horse = 33000 foot-pounds/minute

or 55 pounds 10 feet in 1 second


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## DAVIS081404 (Oct 20, 2006)

Dont get what I am saying wrong. 3 pahse and single phase are differant calcs. However 746 watts is 1hp. Three phase is generally more efficient. The benefit from three phase is that you reduce the amperage draw. Below is in a perfect world.

Single phase load: 746watts @ 240v (746/240) =3.1amps 
Three Phase load: 746 watts @ 240v (746/ {240 X 1.73} = 1.8 amps


(3 phase worth the extra money when you get into larger loads in a home it would not be practicle)

Also in none of these calcs have we used power factor. VARS make a differance (Watts VS Volt Amps).


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## Sparky Joe (Apr 29, 2006)

DAVIS081404 said:


> Dont get what I am saying wrong. 3 pahse and single phase are differant calcs. However 746 watts is 1hp. Three phase is generally more efficient. The benefit from three phase is that you reduce the amperage draw. Below is in a perfect world.
> 
> Single phase load: 746watts @ 240v (746/240) =3.1amps
> Three Phase load: 746 watts @ 240v (746/ {240 X 1.73} = 1.8 amps
> ...


So finally now you see what I am getting at; 1.8x240=432 watts, not 746, finally there is a reason for a three phase world.

About power factor and volt amps reactive, notice what I said about volts and amps being "slightly out of phase". In this inductive case it's a lagging power factor (eli)


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## CE1 (Dec 30, 2005)

The constant for 3 Phase Power = 1.73. All formulas for single phase power can be used for 3 Phase with the additional multiplication of 1.73 when working with Volts and Amps.
HP is just a standard unit of measure and you have to apply it to a formula to calculate another standard unit of measure.

Horse Power (Single Phase) = (Volts x Amps x Efficiency x Power Factor) / 746 
Horse Power (3 Phase) = (Volts x Amps x 1.73 x Efficiency x Power Factor) / 746 

So in theory:
1 HP single phase = 746 watts 
1 HP 3 Phase = 1,290 watts 

Carry On!

You also have to remember that the *output* is 1 HP and in order to get this you have to supply an *input* of 746 watts for single phase and 1,290 watts for 3 phase.


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## DAVIS081404 (Oct 20, 2006)

CE1 said:


> The constant for 3 Phase Power = 1.73. All formulas for single phase power can be used for 3 Phase with the additional multiplication of 1.73 when working with Volts and Amps.
> HP is just a standard unit of measure and you have to apply it to a formula to calculate another standard unit of measure.
> 
> Horse Power (Single Phase) = (Volts x Amps x Efficiency x Power Factor) / 746
> ...


 

It is not 1290 watts. It is 746 watts. This is a univerasal fact. It cannot be minipulated. The only way to get more than 746 Watts per HP (single phase or Three Phase) is to alter the formula (by changing the efficiency or reactive power). To get 1290watts you simply multiplied your answer for single phase by 1.73. Remember this is theory.

The formula is:

Single Phase:
(E x I X % EFF X PF)/746 =Horse Power

Three Phase:
(E x I X % EFF X PF X 1.73)/746 =Horse Power

To determine this you must know all of the following:

Volts; Amperage; Motor Eff; Power Factor;


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## DAVIS081404 (Oct 20, 2006)

Sparky Joe said:


> So finally now you see what I am getting at; 1.8x240=432 watts, not 746, finally there is a reason for a three phase world.
> 
> About power factor and volt amps reactive, notice what I said about volts and amps being "slightly out of phase". In this inductive case it's a lagging power factor (eli)


No, I am saying;

1.8 x 240 X 1.732=746 watts

The benefit is the reduced amperage draw, which makes a huge differance in a large industrial situation. The ability to reduce conductor size not only as a suply to the motor but internally can significantly change costs. To my knowledge a 3 phase motor is more efficient to run, however it still needs 746watts to produce 1 hp. It just decreases thw differance in your input watts and output watts 

Power Factor can also be a significant factor in efficiency. Utilities fight this all the time. The scenario you talk about above becomes a huge cost to utilities. They spend millions of dollars trying to counter the effect of VARS. Its a huge expense to transport and deliver a AMP and not be able to sell it.


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## CE1 (Dec 30, 2005)

DAVIS081404 said:


> It is not 1290 watts. It is 746 watts. This is a univerasal fact. It cannot be minipulated. The only way to get more than 746 Watts per HP (single phase or Three Phase) is to alter the formula (by changing the efficiency or reactive power). To get 1290watts you simply multiplied your answer for single phase by 1.73. Remember this is theory.
> 
> The formula is:
> 
> ...


I stand Corrected! I did have it right originally but got caught up it analyzing it to much. :notworthy :notworthy :notworthy


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