Watts vs Volt-Amps - huh ??

[Naptown]

Since power factor is a loss wouldn't you divide by that?

[SunEagle]

I am brain dead today
I need to convert 14.1 amps at 208v three phase to watt hours.
Anybody know the formula?

va = amps x the three phase voltage x 1.73. Then you have to multiply by a power factor to get watts. Then multiply by the number of hours it is running.

So va = 14.1 x 208 x 1.73 x pf = watts. Your pf could be as low as 0.75 depending on the pump motor.

[Naptown]

I sell solar.
No sale no income.
Why I pointed out almost a 60% savings with almost no expense I have no idea. No sale for me.
I have a bad habit ( for my income)
of doing the right thing.
Today probably cost me $5000 dollars by suggesting alternatives.
Oh we'll I will sleep we'll tonight

[bcroe]

I am brain dead today. I need to convert 14.1 amps at
208v three phase to watt hours. Anybody know the formula?

At our lab, we had a 3 phase bus. It was listed as 208 3 phase. But there
was a common return, so you got 120VAC (to 100A) from a single line to return.
Going on that, 14.1A from a 120V line to return =1692 VA, times 3 (lines) =
5076 VA. Of course the net current down the return is zero.

You can find what 2 equal currents 120 degrees out of phase = 14.1A total
line current, (might be around 8.1A), multiply that by the line to line 208V
times 3, better get the same answer. Bruce Roe

[inetdog]

This is commercial so VA it is

Significant only if it reduces the max peak demand below the next lower surcharge level. Other than that quantity charge will still be based on watts.

[Naptown]

This is commercial so VA it is

[inetdog]

One

Pool has a 5 HP pump running 24/7
This is for decorative and useless jets
Trying to figure out savings by turning off
This does not affect the filtration system as that is separate

You could also take a quick sanity check by multiplying 5HP times 746 watts if you assume that the motor is fully loaded by the pump. That will give you an upper limit.
The measured current will probably be at a low power factor, and since you will not be paying POCO based on VA, you will have to estimate that factor.

[Naptown]

One

Pool has a 5 HP pump running 24/7
This is for decorative and useless jets
Trying to figure out savings by turning off
This does not affect the filtration system as that is separate

[inetdog]

I am brain dead today
I need to convert 14.1 amps at 208v three phase to watt hours.
Anybody know the formula?

Is that 208Y/120? And the 14.1A is the phase line current, not the load winding current?

If the voltage to ground is 120 and the current in each LN conductor is 14.1, balanced, the power will be 120 x 14.1 x 3, which is also the same as 208 x 14.1 x sqrt(3).

If your 14.1 is the current in each phase-to-phase load, the power is 208 x 14.1 x 3, but the line current will be greater than 14.1 by a factor of sqrt(3).
Now that you have watts, I will let you figure out the watt-hours, since you did not tell me the time factor.

BTW, I find that the trick of multiplying the phase line current times the line to ground voltage and then multiplying by 3 is really easy to remember and gives the same result as the "official" calculation. If nothing else it is a good reality check that you got the other formula correct.

There is no need to work with vectors and sines and cosines, since the amount of power going out the phase lines will be exactly the same for a given current regardless of whether the load is actually delta or wye. You just have to keep in mind which current you are measuring.

[Naptown]

I am brain dead today
I need to convert 14.1 amps at 208v three phase to watt hours.
Anybody know the formula?

[YYP123456]

Yaya123

Hi: hello, your website is very popular, I like it very much

[Robert1234]

Well, inverter wasn't off this morning but it should have been. Battery bank was at 19.4 volts. I shut it down and put the tanks on "life support". System definitely is burning amp-hr based on volt amps. Now to adjust and see what effect it has.

[inetdog]

Well I tried to climb in and close the door but I couldn't fit.

Either find a small kid or put a small PV panel inside and run the wires out.

[SunEagle]

If it is drawing 81 watts without the compressor running, you are looking at an air circulating fan continuing to run or more likely door edge heaters that should be turned off. There may also be a heater that comes on only during the defrost cycle, which you should not try to alter.
Or maybe the light really does stay on when you close the door.

Well I tried to climb in and close the door but I couldn't fit.

Actually the compressor is running when drawing the 81.7 watts adn 1.0 amps but it is very quite. I needed to put my hand on it to feel the vibration. It is one of those Majic Chef probably 4 cu foot. It has a nameplate rating of 120 watts & 1.5 amp at 120 V.

[inetdog]

I should have recorded the VA measurements as well to see how they compared to the other metrics. I will go back and check tomorrow but my voltage is a little high today so the next time all of my measurements may be different. I was surprised with the fan PF being 0.99. It did bounce a little between 0.98 and 1.0 but settled at 0.99.

The KAW is pretty neat but I am still learning about it. The listed accuracies run between 0.2 to 2% depending on which function it is measuring.

I am currently getting a profile of my small frig so I really know what it will take to keep it running on a battery system. It is drawing about 81 watts now but the compressor is not running so I want to get a 24 hour run on it. I am also checking on some 12v Pure Sine wave inverters since my cobra is a Modified Sine wave and will not really run the frig.

If it is drawing 81 watts without the compressor running, you are looking at an air circulating fan continuing to run or more likely door edge heaters that should be turned off. There may also be a heater that comes on only during the defrost cycle, which you should not try to alter.
Or maybe the light really does stay on when you close the door.