Posted by nicksanspam on May 8, 2007, 5:48 am
Power factor correction caps at 120 volts:
PF .5 .6 .7 .8
watts
100 31.9 24.6 18.8 13.8
200 63.8 49.1 37.6 27.6
300 95.7 73.7 56.4 41.4
400 127.6 98.2 75.2 55.3
500 159.5 122.8 94 69.1
600 191.4 147.4 112.8 82.9
700 223.3 171.9 131.5 96.7
800 255.2 196.5 150.3 110.5
900 287.1 221 169.1 124.3
1000 319 245.6 187.9 138.2
^ m i c r o f a r a d s ^
Power factor correction caps at 277 volts:
PF .5 .6 .7 .8 (uncorrected)
watts
100 6 4.6 3.5 2.6
200 12 9.2 7.1 5.2
300 18 13.8 10.6 7.8
400 24 18.4 14.1 10.4
500 29.9 23 17.6 13
600 35.9 27.7 21.2 15.6
700 41.9 32.3 24.7 18.1
800 47.9 36.9 28.2 20.7
900 53.9 41.5 31.7 23.3
1000 59.9 46.1 35.3 25.9
^ m i c r o f a r a d s ^
C = 2653xPxsqrt(1-PF^2)/(V^2*PF) microfarads
Cap values are proportional to power. For instance, the table above shows
2.6 uF for 100 watts with a 0.8 power factor before correction and about
26 uF for 1000 watts with a 0.8 power factor before correction.
The $199 TES 3079K clamp-on meter from Optimum Energy works
up to 600 V and 600 kW and also measures capacitance...
Nick
Posted by mg on May 11, 2007, 12:15 am
On May 8, 3:48 am, nicksans...@ece.villanova.edu wrote:
> Power factor correction caps at 120 volts:
> PF .5 .6 .7 .8
> watts
> 100 31.9 24.6 18.8 13.8
> 200 63.8 49.1 37.6 27.6
> 300 95.7 73.7 56.4 41.4
> 400 127.6 98.2 75.2 55.3
> 500 159.5 122.8 94 69.1
> 600 191.4 147.4 112.8 82.9
> 700 223.3 171.9 131.5 96.7
> 800 255.2 196.5 150.3 110.5
> 900 287.1 221 169.1 124.3
> 1000 319 245.6 187.9 138.2
> ^ m i c r o f a r a d s ^
> Power factor correction caps at 277 volts:
> PF .5 .6 .7 .8 (uncorrected)
> watts
> 100 6 4.6 3.5 2.6
> 200 12 9.2 7.1 5.2
> 300 18 13.8 10.6 7.8
> 400 24 18.4 14.1 10.4
> 500 29.9 23 17.6 13
> 600 35.9 27.7 21.2 15.6
> 700 41.9 32.3 24.7 18.1
> 800 47.9 36.9 28.2 20.7
> 900 53.9 41.5 31.7 23.3
> 1000 59.9 46.1 35.3 25.9
> ^ m i c r o f a r a d s ^
> C = 2653xPxsqrt(1-PF^2)/(V^2*PF) microfarads
> Cap values are proportional to power. For instance, the table above shows
> 2.6 uF for 100 watts with a 0.8 power factor before correction and about
> 26 uF for 1000 watts with a 0.8 power factor before correction.
> The $199 TES 3079K clamp-on meter from Optimum Energy works
> up to 600 V and 600 kW and also measures capacitance...
> Nick
I'm not sure if I understand that. Say, for example, that I want to
put a cap on my 120V swamp cooler and measure it at 800W with a PF of
0.6. Does that mean, then, that all I need to do is put a 196.5
microfarad, 120V cap between the power and neutral terminals and the
power factor will be close to 1?
Is it all just that simple or are there other things I need to know? I
wonder if that has any effect on the surge current?
I do actually have a Kill A Watt meter, by the way and my swamp cooler
motor has a plug on the end of it.
Posted by nicksanspam on May 11, 2007, 7:05 am
>> Power factor correction caps at 120 volts:
>>
>> PF .5 .6 .7 .8
>> watts
>>
>> 800 255.2 196.5 150.3 110.5
>> ^ m i c r o f a r a d s ^
>>
>> C = 2653xPxsqrt(1-PF^2)/(V^2*PF) microfarads
>>
>... Say, for example, that I want to put a cap on my 120V swamp cooler
>and measure it at 800W with a PF of 0.6. Does that mean, then, that
>all I need to do is put a 196.5 microfarad, 120V cap between the power
>and neutral terminals and the power factor will be close to 1?
Sure. C = 2653x800xsqrt(1-0.6^2)/(120^2*0.6) = 196.5 microfarads
You might parallel smaller caps. This won't save much residential
grid-tie money.
>Is it all just that simple or are there other things I need to know?
You might want to shoot for a bit less than 1, since that makes resonance.
>I wonder if that has any effect on the surge current?
One Sprague engineer said he thought that would not be a problem.
A series choke might lessen worries about fusing switch contacts.
>I do actually have a Kill A Watt meter, by the way and my swamp cooler
>motor has a plug on the end of it.
Hey, try it :-) Then move your swamp cooler indoors and turn it on
with a room temp thermostat when the indoor temp reaches 80 F and
turn on a small exhaust fan when the indoor RH reaches 56% :-)
Nick
Posted by mg on May 11, 2007, 2:16 pm
On May 11, 5:05 am, nicksans...@ece.villanova.edu wrote:
> >> Power factor correction caps at 120 volts:
> >> PF .5 .6 .7 .8
> >> watts
> >> 800 255.2 196.5 150.3 110.5
> >> ^ m i c r o f a r a d s ^
> >> C = 2653xPxsqrt(1-PF^2)/(V^2*PF) microfarads
> >... Say, for example, that I want to put a cap on my 120V swamp cooler
> >and measure it at 800W with a PF of 0.6. Does that mean, then, that
> >all I need to do is put a 196.5 microfarad, 120V cap between the power
> >and neutral terminals and the power factor will be close to 1?
> Sure. C = 2653x800xsqrt(1-0.6^2)/(120^2*0.6) = 196.5 microfarads
> You might parallel smaller caps. This won't save much residential
> grid-tie money.
> >Is it all just that simple or are there other things I need to know?
> You might want to shoot for a bit less than 1, since that makes resonance.
> >I wonder if that has any effect on the surge current?
> One Sprague engineer said he thought that would not be a problem.
> A series choke might lessen worries about fusing switch contacts.
> >I do actually have a Kill A Watt meter, by the way and my swamp cooler
> >motor has a plug on the end of it.
> Hey, try it :-) Then move your swamp cooler indoors and turn it on
> with a room temp thermostat when the indoor temp reaches 80 F and
> turn on a small exhaust fan when the indoor RH reaches 56% :-)
> Nick
Thanks a lot nick. I know I wouldn't save anything on the electric
bill, but I'm assuming a PF corrected motor would draw less current
from a standby generator.
XML site map
> PF .5 .6 .7 .8
> watts
> 100 31.9 24.6 18.8 13.8
> 200 63.8 49.1 37.6 27.6
> 300 95.7 73.7 56.4 41.4
> 400 127.6 98.2 75.2 55.3
> 500 159.5 122.8 94 69.1
> 600 191.4 147.4 112.8 82.9
> 700 223.3 171.9 131.5 96.7
> 800 255.2 196.5 150.3 110.5
> 900 287.1 221 169.1 124.3
> 1000 319 245.6 187.9 138.2
> ^ m i c r o f a r a d s ^
> Power factor correction caps at 277 volts:
> PF .5 .6 .7 .8 (uncorrected)
> watts
> 100 6 4.6 3.5 2.6
> 200 12 9.2 7.1 5.2
> 300 18 13.8 10.6 7.8
> 400 24 18.4 14.1 10.4
> 500 29.9 23 17.6 13
> 600 35.9 27.7 21.2 15.6
> 700 41.9 32.3 24.7 18.1
> 800 47.9 36.9 28.2 20.7
> 900 53.9 41.5 31.7 23.3
> 1000 59.9 46.1 35.3 25.9
> ^ m i c r o f a r a d s ^
> C = 2653xPxsqrt(1-PF^2)/(V^2*PF) microfarads
> Cap values are proportional to power. For instance, the table above shows
> 2.6 uF for 100 watts with a 0.8 power factor before correction and about
> 26 uF for 1000 watts with a 0.8 power factor before correction.
> The $199 TES 3079K clamp-on meter from Optimum Energy works
> up to 600 V and 600 kW and also measures capacitance...
> Nick