Guest msb Posted January 17, 2006 Report Share Posted January 17, 2006 Hi, Our last power bill shows the PF as 2.38. Is this at all theoretically/practically possible? Or is it probably a mistake in the meter reading? In the previous bill it was 0.56. We have now added an Automatic Power Factor controller. Link to comment Share on other sites More sharing options...
ram14375 Posted January 17, 2006 Report Share Posted January 17, 2006 hi,Power factor can never exceed unity as it is the ratio of active power to apparent power.it can go in leading or lagging not above unity at any case.It should be the mistake of the meter. if u have power factor incentive you try to claim the same from your supplier for the above pf Link to comment Share on other sites More sharing options...
marke Posted January 17, 2006 Report Share Posted January 17, 2006 Hello msb I agree with ram14375.Power factor is the ratio between KW and KVA and it is not possible for this to exceed 1. If it did, we would all do it and be making money!! Distortion power factor is always less than or equal to one, and displacment power factor can be positive or negative and is in the range of -1 to +1. Best regards, Mark Empson | administratorSkype Contact = markempson | phone +64 274 363 067LMPForum | Power Factor | L M Photonics Ltd | Empson family | Advanced Motor Control Ltd | Pressure Transducers | Smart Relay | GSM Control | Mark Empson Website | AuCom | Soft Starters Link to comment Share on other sites More sharing options...
Guest msb Posted January 18, 2006 Report Share Posted January 18, 2006 Thanks for your replies. I just checked the energy meter and the readings are as following: PF1 = 0.92PF2 = -0.99 What does the negative reading mean? Is this normal or are my capacitors wired in wrong? How do I rectify this? Thanks in advance. Link to comment Share on other sites More sharing options...
marke Posted January 18, 2006 Report Share Posted January 18, 2006 Hello msb Generally, an inductive power factor is positive and a capacitive power factor is negative. If there is a problem with the ct connections, you can get a negative pf reading. A capacitive power factor means that you have applied too much capacitance. In a bulk corection installation, this is not usually a problem, however in a static corection case, this is potentially very dangerous.Reduce tha amount of capacitance, and the pf should go positive. Best regards, Mark Empson | administratorSkype Contact = markempson | phone +64 274 363 067LMPForum | Power Factor | L M Photonics Ltd | Empson family | Advanced Motor Control Ltd | Pressure Transducers | Smart Relay | GSM Control | Mark Empson Website | AuCom | Soft Starters Link to comment Share on other sites More sharing options...
chris1373 Posted August 28, 2007 Report Share Posted August 28, 2007 What is the diference betwin a "bulk correction" and a "static correction"? Thanks. Chris. Hello msb Generally, an inductive power factor is positive and a capacitive power factor is negative. If there is a problem with the ct connections, you can get a negative pf reading. A capacitive power factor means that you have applied too much capacitance. In a bulk corection installation, this is not usually a problem, however in a static corection case, this is potentially very dangerous. Reduce tha amount of capacitance, and the pf should go positive. Best regards, Link to comment Share on other sites More sharing options...
marke Posted August 28, 2007 Report Share Posted August 28, 2007 Hello Chris Check out http://www.lmphotonics.com/pwrfact.htm which gives descriptions of static and bulk correction. Essentially, static correction is applied to each motor and is controlled by the motor starter, and bulk correction is applied at the point of supply, submain or similar and is controlled by an automatic controller. Best regards, Mark Empson | administratorSkype Contact = markempson | phone +64 274 363 067LMPForum | Power Factor | L M Photonics Ltd | Empson family | Advanced Motor Control Ltd | Pressure Transducers | Smart Relay | GSM Control | Mark Empson Website | AuCom | Soft Starters Link to comment Share on other sites More sharing options...
ravi agnihotri Posted August 31, 2007 Report Share Posted August 31, 2007 Hi, Our last power bill shows the PF as 2.38. Is this at all theoretically/practically possible? Or is it probably a mistake in the meter reading? In the previous bill it was 0.56. We have now added an Automatic Power Factor controller. Link to comment Share on other sites More sharing options...
ravi agnihotri Posted August 31, 2007 Report Share Posted August 31, 2007 basically power factor=real power/ apparent power real power= voltage*current*cos@ =v*i*cos@ apparent power= v*i so, power factor = (v*i*cos@)/(v*i) =cos@ & we know that max value of cosine can naver exceed unity.......... so power factor can never be more than 1. Link to comment Share on other sites More sharing options...
marke Posted August 31, 2007 Report Share Posted August 31, 2007 Hello ravi agnihotri This is true if you are considering displacement power factor. The Cosine does not apply to distortion power factor, but the outcome is the same, power factor can not be greater than 1. Best regards, Mark Empson | administratorSkype Contact = markempson | phone +64 274 363 067LMPForum | Power Factor | L M Photonics Ltd | Empson family | Advanced Motor Control Ltd | Pressure Transducers | Smart Relay | GSM Control | Mark Empson Website | AuCom | Soft Starters Link to comment Share on other sites More sharing options...
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