10-20-2010 10:18 AM
Hello,
What is the test frequency for the resistance measurement on the LCRmeter NI 4072 ?
How can i change it to set this frequency to 1kHz ?
Thank you
10-21-2010 08:44 AM
Hello YannickDannel,
You can perform a resistance measurement in DC or AC to determine the response of resistance (just one fréquency, no sweep);
You can set the 1KHz exitation by soft.
For more information do not hesitate to call technical service : 01.57.66.24.24
Best Regards,
Rémi D.
National Instruments France
10-21-2010 10:25 AM
Hello,
Thank you for your response.
If I undestand, I can use the NI 4072 LCR meter to do an impedance measurement at 1 kHZ ?
Currently, we use the Agilent U1731A LCR meter do to the the impedance measurement. This device use a sinusoidal AC to mesure the impedance. the characteristics of this signal is 1kHz frequency and amplitude 1.4V peak to peak.
The NI 4072 LCR meter it is able to do an impedance measurement with this characteristics ?
In this document :
http://digital.ni.com/public.nsf/allkb/9DADFD5D9B271912862571F6007A8ECC?OpenDocument
It is written that the NI 4072 makes resistance measurements using a constant-current technique and uses a multi-tone AC current source as the excitation signal necessary to measure capacitance and inductance. I undestand that it is impossible to do an impedance measurement with the characteristics I want.
10-21-2010 10:50 AM
Hello Yannick,
The measurement method used by your Agilent LCR meter is different than the measurement method used by the PXI-4072. The PXI-4072 uses a patented method to measure inductance and capacitance. It uses a square wave signal instead of a sinusoidal, and extracts the inductance and capacitance values using the information from the sinusoidal content of a square wave (like a fourier expansion). It does not return the impedance value (which includes both the real and imaginary part) but only the reactive part.
You can find more information about the method in the following white paper: http://zone.ni.com/devzone/cda/tut/p/id/3713
Another link of interest: http://zone.ni.com/devzone/cda/tut/p/id/3078
The resistance measurements in the PXI-4072 are done separately from the capacitance and inductance measurements. These measurements use a DC excitation current. The current used depends on the range you choose (refer to the specifications for the list of current source value used per range).
- Claudia
10-22-2010 09:27 AM
Thank you Claudia.
I can't use this board do to a impedance measurement in my condition.
Another solution is to use an Arbitrary Function Generators (NI 5402) to generate a sine wave of 1kHz frequency and amplitude 1.4V peak to peak if it is possible. And measure the rms current with an analog input and use U = R.I to calculate the impedance. Can it possible to do this with the NI device ?
10-22-2010 10:17 AM
You could do it, but you will need another acquisition channel. For the measurements to be useful, you will also need to calculate the uncertainites of your measurements based on your measurement system, accuracy of your digitized waveforms, how simultaneous are yor waveform acquisitions, etc.
The PXI-4072 is capable of working as an isolated digitizer (up to 1.8 MSamples/sec), and it can digitize voltage or current waveforms. However, it can only digitize one of these at a time. You would get the best results from digitizing both waveforms simultaneously.
NI ELVIS II (module meant for educational facilities) performs an impedance measurement similar to what you want to do. It uses its ARB to generate a sine wave, digitizes both the voltage excitation signal and the current flowing through the DUT (device under test), and then calculates the impedance of the DUT using the amplitude of the two signals and their phase lag respect to each other. You can read more about it in its User Manual, Appendix A, Page A-33: http://www.ni.com/pdf/manuals/374629b.pdf.
10-26-2010 04:42 AM
Ok, I can use the NI ELVIS II.
But I must use the ARB to generate a sine wave and the impedance analyzer in the same time. I must have 2 digital output (0/5V or 0/24V) and 2 analog input (1 input 0/5V and 1 input 0/10V) with a sample rate of 10kHz. All must be run at the same time. The NI ELVIS can do it ???
Instead of using the NI ELVIS, can I use an Arbitrary Function Generators (NI 5402), a module to measure the rms current, a digital output module (0/5V or 0/24V) and a analog input module (1 input 0/5V and 1 input 0/10V) ??? And which module can I use to do it ???