fancy102 Posted November 23, 2007 Report Share Posted November 23, 2007 hi..I would like to construct a circuit that can measure the power factor of a system. I would like to use comparator, analogue switch and PIC controller to measure the power factor..the output of the analogue switch is voltage(analogue form) So,my problem is how to measure the current of the system so that i can get the voltage and current to measure the power factor?thanks Link to comment Share on other sites More sharing options...
marke Posted November 23, 2007 Report Share Posted November 23, 2007 Hello fancy102 Welcome to the forum. Have a look at Power Factor Measurement Does this help?? 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...
fancy102 Posted November 24, 2007 Author Report Share Posted November 24, 2007 yaya...thanks a lot!!it does help but i still facing problem... if i constuct a circuit as shown..then where should i measure the current?the OP-AMP already change the current into voltage form.. my question is if both of my control signal n input into the anlogue switch(4066) are voltage......then where to get my current? thanks for helping..ur kindness are really appreciated... circuit are: output of OPAMP 356 become input into comparator(V) }become input of analogue switch(input signal) + ootput of compatar(V) } become input of analogue switch (control signal) Link to comment Share on other sites More sharing options...
marke Posted November 24, 2007 Report Share Posted November 24, 2007 Hello fancy102 To measure displacement power factor, you need to measure the angle between the voltage and the current and the easiest way to do this is to create a square wave that is representative of the polarity of the voltage waveform, and another square wave that is representative of the polarity of the current waveform. - you do not need to measure that actual voltage or current, just the angle between them. You can use an XOR gate to combine the waveforms, or you can use a timer in a micro to measure the time between the positive transitions. You could then output this as a PWM waveform and filter to get an analogue output. If you are looking at measuring more than just power factor, then the output of the CT can be monitored by additional circuitry which can give you the current magnitude. If this is not what you are looking for, then please explain what you are looking for and why so that we fully understand what you want and we may be able to help. 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...
fancy102 Posted November 30, 2007 Author Report Share Posted November 30, 2007 Dear marke, thanks for your guidance..i had some idea about the measurement... so,what i need to do is just measure the phase (angle of current and voltage)...then through programming ( PIC )my output will send to the LCD display... ok..really thanks for helping.. Link to comment Share on other sites More sharing options...
keoshiro Posted February 20, 2008 Report Share Posted February 20, 2008 hello fancy102, Link to comment Share on other sites More sharing options...
keoshiro Posted February 20, 2008 Report Share Posted February 20, 2008 Hello fancy102, Currently, im doing a project on power factor correction that is similar to yours and now facing some problems. Actually, i planning to use a current transducer, comparator, phase detector and capacitor banks to design the project but facing many problems. Do you mind share with me about your circuit design so i can take it as a reference? Here is my msn, keolim85@hotmailcom, and my email is caesarlim85@yahoo.com I would appreciate to hear from you, thanks. Link to comment Share on other sites More sharing options...
far8z Posted July 25, 2008 Report Share Posted July 25, 2008 Dear marke, thanks for your guidance..i had some idea about the measurement... so,what i need to do is just measure the phase (angle of current and voltage)...then through programming ( PIC )my output will send to the LCD display... ok..really thanks for helping.. Currently. i'm doing my final project on how to measure power factor using PIC microcontroller...now, i'm having problem in designing the circuit on how to measure the PF..So, would you mind to share with me about your circuit design so i can take it as the reference?..your help is appreciated... Link to comment Share on other sites More sharing options...
far8z Posted July 25, 2008 Report Share Posted July 25, 2008 hi fancy 102; Currently. i'm doing my final project on how to measure power factor using PIC microcontroller...now, i'm having problem in designing the circuit on how to measure the PF..So, would you mind to share with me about your circuit design so i can take it as the reference?..your help is appreciated... Link to comment Share on other sites More sharing options...
far8z Posted July 25, 2008 Report Share Posted July 25, 2008 hi fancy 102; Currently. i'm doing my final project on how to measure power factor using PIC microcontroller...now, i'm having problem in designing the circuit on how to measure the PF..So, would you mind to share with me about your circuit design so i can take it as the reference?..your help is appreciated...my email is far8z@yahoo.com Link to comment Share on other sites More sharing options...
x20a Posted September 29, 2009 Report Share Posted September 29, 2009 hi, i'm also currently doing my final yr project which is correcting the power factor in houses. so i followed the step in reading the power factor found in this forum which convert the sinusoid of voltage and current to a square waveform i'm using op-amp (lm324) to convert the sinusoids the problem is the square waveform will be distorted when the magnitude of voltage grows larger than 1 V :angry: is there any solution for this problem?? please help me :o Link to comment Share on other sites More sharing options...
marke Posted September 29, 2009 Report Share Posted September 29, 2009 If you are using the op amp as a comparator to produce a squarewave output that indicates the polarity of the input, it will not become distorted by a change in input voltage provided that the input voltage does not exceed the supply rails. This can be prevented by using diode clamps. Best regards, Mark. 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...
x20a Posted October 1, 2009 Report Share Posted October 1, 2009 If you are using the op amp as a comparator to produce a squarewave output that indicates the polarity of the input, it will not become distorted by a change in input voltage provided that the input voltage does not exceed the supply rails. This can be prevented by using diode clamps. Best regards, Mark. thx for your reply mark.. hm then i got another question, where do we have to clamp the diode on the circuit?? thx in advance and really appreciated it regards, x20a Link to comment Share on other sites More sharing options...
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