impedance calculation  Power Factor

 User
 Posts: 5
 Joined: Wed Sep 27, 2006 9:51 am
impedance calculation  Power Factor
Hello,
I'm working with a 12 volt AC signal. I have the Voltage on channel A and the TA018 current clamp on channel B
I would like to calculate the impedance using a math channel A/B, and a measurement, but where the current goes through zero, the signal goes out of range. How do I get around this problem?
I'm working with a 12 volt AC signal. I have the Voltage on channel A and the TA018 current clamp on channel B
I would like to calculate the impedance using a math channel A/B, and a measurement, but where the current goes through zero, the signal goes out of range. How do I get around this problem?
Re: impedance calculation
Hi,
I agree, so you want the AC rms value of the impedance? Do also want the reactance and true resistance of circuit as well as phase angle?
See diagram
http://www.nap.edu/openbook/0309057973/ ... 170001.jpg
I agree, so you want the AC rms value of the impedance? Do also want the reactance and true resistance of circuit as well as phase angle?
See diagram
http://www.nap.edu/openbook/0309057973/ ... 170001.jpg
Regards Andrew
Technical Specialist
Technical Specialist

 User
 Posts: 5
 Joined: Wed Sep 27, 2006 9:51 am
Re: impedance calculation
Hello,
Thanks for your reply and the diagram.
Of course, the more information I can get, the better, but I don't actually need more than just the AC rms impedance value because I am only making comparison measurements to a "known good" value. I thought there might be some mathematical technique or connection methodology to get around the problem right within Picoscope.
Thanks for your reply and the diagram.
Of course, the more information I can get, the better, but I don't actually need more than just the AC rms impedance value because I am only making comparison measurements to a "known good" value. I thought there might be some mathematical technique or connection methodology to get around the problem right within Picoscope.
Re: impedance calculation  Power Factor
Hello,
Most of the calculations cannot be done in PicoScope. But the measurements needed can be exported out. And could be easily be done in excel.
See this post on exporting measurement values
topic15481.html?hilit=batch
First you need to setup your channels and the measurements needed
See the screen shot and example psdata file with
Channel A for Volts
Channel B for Amps
Maths channel  ChA x ChB (Instantaneous Power)
The measurements that are exported are
Volts rms
Current(Amps)  rms
Apparent Power which is the DC average of Instantaneous Power (Volts x Amps)
Now follow the calculations in the attached pdf. Here is Excel file with the calculations included I have not used complex numbers but you could do for some of the calculations.
Most of the calculations cannot be done in PicoScope. But the measurements needed can be exported out. And could be easily be done in excel.
See this post on exporting measurement values
topic15481.html?hilit=batch
First you need to setup your channels and the measurements needed
See the screen shot and example psdata file with
Channel A for Volts
Channel B for Amps
Maths channel  ChA x ChB (Instantaneous Power)
The measurements that are exported are
Volts rms
Current(Amps)  rms
Apparent Power which is the DC average of Instantaneous Power (Volts x Amps)
Now follow the calculations in the attached pdf. Here is Excel file with the calculations included I have not used complex numbers but you could do for some of the calculations.
 Attachments

 AC vectors and Power factors.psdata
 AC vectors and Power Factor
 (1.03 MiB) Downloaded 193 times
Regards Andrew
Technical Specialist
Technical Specialist
Re: impedance calculation  Power Factor
We now have a formula to give a RMS value using a maths channel.
Adding '+freq(A)freq(A)' to it stops the start of the maths channel starting at a lower value.
When using the measures on these maths channels you need to set 'between time rulers' and move time rulers to exclude the start and the end of the maths channel.
I have attached a updated psdata file with these maths channels included.
Channel A must be used for Voltage
Channel B must be used for Current Remember you can still take the three measurement values
'AC RMS' of Channel A for Volts
'AC RMS' of Channel B for Amps
'DC Average' of Maths channel  ChA x ChB (Instantaneous Power)
As before and enter these into the spreadsheet to check the calculations are correct.
Math channel formulas
RMS value (channel A)=
Power factor =
PF in degrees =
I suggest turning off maths channels you don't need, or adding more 'view' windows if you need more maths channels (VA, Reactance X, etc).
If you are going to be doing three phase with 4824 remember a 'view' window only supports 8 channels/maths channels.
Code: Select all
sqrt(integral(A^2)/T)
When using the measures on these maths channels you need to set 'between time rulers' and move time rulers to exclude the start and the end of the maths channel.
I have attached a updated psdata file with these maths channels included.
Channel A must be used for Voltage
Channel B must be used for Current Remember you can still take the three measurement values
'AC RMS' of Channel A for Volts
'AC RMS' of Channel B for Amps
'DC Average' of Maths channel  ChA x ChB (Instantaneous Power)
As before and enter these into the spreadsheet to check the calculations are correct.
Math channel formulas
RMS value (channel A)=
Code: Select all
sqrt(integral(A^2)/T)+freq(A)freq(A)
Code: Select all
((integral((abs(A*B)))/T)+freq(A)freq(A))/((sqrt(integral((A)^2)/T)+freq(A)freq(A))*(sqrt(integral((B)^2)/T)+freq(B)freq(B)))
Code: Select all
180/pi(acos(((integral((abs(A*B)))/T)+freq(A)freq(A))/((sqrt(integral((A)^2)/T)+freq(A)freq(A))*(sqrt(integral((B)^2)/T)+freq(B)freq(B)))))
If you are going to be doing three phase with 4824 remember a 'view' window only supports 8 channels/maths channels.
Regards Andrew
Technical Specialist
Technical Specialist
Re: impedance calculation  Power Factor
Hi Andrew,
I am doing a frequency sweep for capacitance and inductance separately.
I want to use FRA and measure Impedance and power versus frequency.
What is the standard way of doing this?
Thanks,
Vahid
I am doing a frequency sweep for capacitance and inductance separately.
I want to use FRA and measure Impedance and power versus frequency.
What is the standard way of doing this?
Thanks,
Vahid
Re: impedance calculation  Power Factor
These maths channels won't in FFT mode in PicoScope 6.
So I would try using the FRA4Picoscope with this new tool
https://www.eevblog.com/forum/testgear/ ... msg2190516
So I would try using the FRA4Picoscope with this new tool
https://www.eevblog.com/forum/testgear/ ... msg2190516
Regards Andrew
Technical Specialist
Technical Specialist