All About Circuits Forum  

Go Back   All About Circuits Forum > Electronics Forums > The Projects Forum

Notices

The Projects Forum Working on an electronics project and would like some suggestions, help or critiques? If you would like to comment or assist others with their projects, this is the place to do it.

Reply   Post New Thread
 
Thread Tools Display Modes
  #1  
Old 03-11-2008, 06:03 AM
fancy102 fancy102 is offline
Junior Member
 
Join Date: Dec 2007
Posts: 26
Default leading or lagging power factor

hi..i am carrying out power factor measurement system and i need to know the power quality.

my problem is how can i know the current is leading the voltage or lagging the voltage?i can know it through ossiloscope only?still got any other way to know current leading or lagging voltage?thanks
Reply With Quote
  #2  
Old 03-11-2008, 02:06 PM
thingmaker3's Avatar
thingmaker3 thingmaker3 is offline
Super Moderator
 
Join Date: May 2005
Location: Rural, Oregon GMT -8
Posts: 5,072
Blog Entries: 6
Default

"ELI the ICE man." Current lags voltage in an inductive circuit. Current leads voltage in a capacitive circuit.
__________________
"I want to establish in your mind very clearly that you must not think I deny all that I do not admit. On the contrary, I think there are many things which may be true, and which I shall receive as such hereafter, though I do not as yet receive them; but that is not because there is any proof to the contrary, but that the proof in the affirmative is not yet sufficient for me"
- Michael Faraday
Reply With Quote
  #3  
Old 03-11-2008, 04:32 PM
mrmount mrmount is offline
Member
 
Join Date: Dec 2007
Posts: 59
Default

You can use power factor meter if you want!
Reply With Quote
  #4  
Old 03-12-2008, 12:19 AM
fancy102 fancy102 is offline
Junior Member
 
Join Date: Dec 2007
Posts: 26
Default

I am doing the power factor metre...so i would like to show the lagging or leading to the user...so except ossilocope i cant know leading or lagging through calculation?
Reply With Quote
  #5  
Old 03-12-2008, 01:47 AM
mik3's Avatar
mik3 mik3 is offline
Senior Member
 
Join Date: Feb 2008
Location: Cyprus, but now in UK (GMT+0)
Posts: 4,846
Blog Entries: 9
Default

Quote:
Originally Posted by fancy102 View Post
hi..i am carrying out power factor measurement system and i need to know the power quality.

my problem is how can i know the current is leading the voltage or lagging the voltage?i can know it through ossiloscope only?still got any other way to know current leading or lagging voltage?thanks
You can connect a very low resistor (lets say 1 ohm or less, take care it can handle the power dissipation ) in series with the load. Then monitor the voltage across the resistor with an amplifier which drives a led. Also monitor the voltage across your load with an amplifier too or if it does not need amplification use a buffer which again will drive a led. Note that both the amplifier and buffer must have high input impedance.

Then with this method you will see which led goes to full illumination first.
If the led from the resistor goes bright first it means that you have a capacitive load and the power factor is leading
if the led from the load goes on first it means you have an inductive load and the power factor is lagging.

Note: make the appropriate connections to the buffer and dont connect it directly to the load if it high voltage.
Reply With Quote
  #6  
Old 03-13-2008, 11:51 PM
fancy102 fancy102 is offline
Junior Member
 
Join Date: Dec 2007
Posts: 26
Default

u mean connect a LED series to the load? then the other one connect to the ouput of the comparator(current)?

why do i need buffer??sorry for the poor knowledge...thanks
Reply With Quote
  #7  
Old 03-14-2008, 12:09 AM
mik3's Avatar
mik3 mik3 is offline
Senior Member
 
Join Date: Feb 2008
Location: Cyprus, but now in UK (GMT+0)
Posts: 4,846
Blog Entries: 9
Default

Quote:
Originally Posted by fancy102 View Post
u mean connect a LED series to the load? then the other one connect to the ouput of the comparator(current)?

why do i need buffer??sorry for the poor knowledge...thanks
why do you need to know this about the power factor?
Reply With Quote
  #8  
Old 03-14-2008, 02:12 AM
fancy102 fancy102 is offline
Junior Member
 
Join Date: Dec 2007
Posts: 26
Default

because i am carrying out power factor measurement system. i need to know the power factor of the system and current is leading or lagging...
Reply With Quote
  #9  
Old 03-15-2008, 11:46 PM
fancy102 fancy102 is offline
Junior Member
 
Join Date: Dec 2007
Posts: 26
Default

sorry to ask again...the phase angle of the power factor should not more than 90 degrees no matter what is the load?is this correct?

if it is capacitive than should negative phase angle and if inductive than should be positive phase angle?is the concept correct??

thanks a lot!!
Reply With Quote
  #10  
Old 01-07-2010, 08:56 AM
hitmen hitmen is offline
Senior Member
 
Join Date: Sep 2008
Posts: 156
Default

sorry to ask again...the phase angle of the power factor should not more than 90 degrees no matter what is the load?is this correct? (Not sure never encountered before)

if it is capacitive than should negative phase angle and if inductive than should be positive phase angle?is the concept correct?? (yes)
Reply With Quote
Reply   Post New Thread

Tags
, , ,


Related Site Pages
Section Title
Worksheet AC power
Worksheet Inductive reactance
Textbook Synchronous condenser : Ac Motors
Textbook Practical power factor correction : Power Factor
Textbook Calculating power factor : Power Factor
Textbook Mutual inductance and basic operation : Transformers
Worksheet Kirchhoff's Laws
Textbook AC capacitor circuits : Reactance And Impedance -- Capacitive
Video Lecture Sine Wave Characteristics (cont) - Alternating Current
Textbook AC inductor circuits : Reactance And Impedance -- Inductive


Similar Threads
Thread Thread Starter Forum Replies Last Post
Distortion Power factor bhupathi111 Homework Help 1 02-28-2014 06:18 AM
Split phase residential power and power factor JamesL The Projects Forum 12 07-04-2012 11:13 PM
Determining leading or lagging power factor raz Math 9 08-03-2011 10:28 PM
Power Factor Correction - Single Phase Induction Motors Zaraphrax Homework Help 2 10-01-2009 02:14 PM
POWER FACTOR PROBLEM! HELP PLEASE ASAP!! mal1990p Homework Help 13 03-11-2009 03:58 AM

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT. The time now is 01:39 PM.


User-posted content, unless source quoted, is licensed under a Creative Commons Public Domain License.
Powered by vBulletin
Copyright ©2000 - 2014, vBulletin Solutions, Inc.