Power Factor & VD
- Thread starter Ken9876
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Thanks, Bob.Smart $ said:
Here it is:
View attachment 176
Is there any significance to the little square-looking object near e_S?
Am I correct in assuming the angle between e_S and e_R vectors represent conductor pf?
kingpb
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- SE USA as far as you can go
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The drawing you are using, or one similar is also produced in Elements of Power System Analysis, and it specifically states that the magnitude of IR and IX are exaggerated in order to illustrate the point more clearly. The actual effect of the offset due to line impedance in the real world would be negligible.
Line impedance negligible? Impedence combines resistive, reactive, and inductive components. Perhaps you meant line reactance? If "line impedance in the real world would be negligible" is truly valid, that would make this whole discussion moot, not to mention VD calculations for any circuit.kingpb said:
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kingpb
Senior Member
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- SE USA as far as you can go
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Please reread what I wrote. It does not say the line impedance is negligible, I stated that the offset is negligible.Smart $ said:
BTW: Thanks for reminding me that impedance is made up of resistance and reactance. I guess I didn't remember that without "X" you don't have a power factor, which means you don't have an offset, which means the offset would be negligible.
Spend a little more time reading, and a little less time trying to be so Smart!
jcormack
Member
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- Pennsylvania
The original question was this:
Does a very poor power factor have an effect on voltage drop? If so how much influence does it play and how would one calculate for voltage drop with a poor power factor.
I do not see where that specifically implies voltage drop across just the conductors. The very simple answer is this - YES! Poor power factor has a significant impact on system voltage drop (voltage regulation). If this were not the case the capacitor companies would be out of business. Voltage drop is not caused just by the real component, as seen from the equations - but by the resultant vector - What these equations don't show is the total system impact. Go to some transformer sites and review some transformer data. Transformers work MUCH better when dealing with currents that have an angle close to that of the voltage applied, when the current required by the load is highly lagging, or leading, then the voltage regulation of the transformer is greatly impacted. Most large transformers will have spec sheets showing voltage regulation/PF. This goes all the way back through every transformer between you and the utility generator - that is why power factor correction capacitors are best when installed as close to the load (motor) they are to be used for - and they should be switched on/off with the motor load, if practical - that way the inductive current required by the motor is supplied by the locally installed capacitors, not the grid. I deal with large industrial power, and often the first thing I do to correct voltage regulation issuses is to improve the site's power factor.
Does a very poor power factor have an effect on voltage drop? If so how much influence does it play and how would one calculate for voltage drop with a poor power factor.
I do not see where that specifically implies voltage drop across just the conductors. The very simple answer is this - YES! Poor power factor has a significant impact on system voltage drop (voltage regulation). If this were not the case the capacitor companies would be out of business. Voltage drop is not caused just by the real component, as seen from the equations - but by the resultant vector - What these equations don't show is the total system impact. Go to some transformer sites and review some transformer data. Transformers work MUCH better when dealing with currents that have an angle close to that of the voltage applied, when the current required by the load is highly lagging, or leading, then the voltage regulation of the transformer is greatly impacted. Most large transformers will have spec sheets showing voltage regulation/PF. This goes all the way back through every transformer between you and the utility generator - that is why power factor correction capacitors are best when installed as close to the load (motor) they are to be used for - and they should be switched on/off with the motor load, if practical - that way the inductive current required by the motor is supplied by the locally installed capacitors, not the grid. I deal with large industrial power, and often the first thing I do to correct voltage regulation issuses is to improve the site's power factor.
Actually it doesn't matter whether you were stating offset due to line impedance being negligible, or the line impedance itself negligible. The result is the same... The statement is not concise enough to elicit distinction. Yes, I have reread it... Yes, I mistook the subject of your statement. Only through implicit remark am I discerning your intent. Nevertheless, you did not specify what offset. You could have been referring to voltage offset, rather a pf-theta offset, or both. Suffice it to say, it was unclear to mekingpb said:Please reread what I wrote. It does not say the line impedance is negligible, I stated that the offset is negligible.
BTW: Thanks for reminding me that impedance is made up of resistance and reactance. I guess I didn't remember that without "X" you don't have a power factor, which means you don't have an offset, which means the offset would be negligible.
Spend a little more time reading, and a little less time trying to be so Smart!
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