Can I measure AC voltage using FP-AI-102? I want to measure in the range of 0-120 VAC

[Micha123]

Can I measure AC voltage using FP-AI-102? I want to measure in the range of 0-120 VAC

[Aaron_G]

The [c]FP-AI-102 modules can measure up to +/-120 Volts. The [c]FP-AI-102 module reads each channel at ~2.8 ms intervals. Any value above or below +/-120 Volts will return an Out of Range error. The module does not report RMS voltage, only instantaneous voltage, so it is better suited to meauring DC voltage.

If you are wanting to measure 120 VAC RMS, then it will not work. If you want 120 VAC where 120 V is the peak voltage, then it may work, but you will be getting values at any point along the curve so you will probably have to do a Min/Max on a number of readings to get the peak voltages.

All in all, the [c]FP-AI-102 modules will probably not meet your needs.

Regards,
Aaron

[Micha123]

Thanks Aaron!
Yes I am trying to measure 120VAC RMS. Does it make any sence to have a sub VI in my program to calculate the RMS voltage, or will this slow down my program? Is there an easier way for me to measure VAC RMS? Is there Fieldpoint hardware that would better for this application then the [c]FP-AI-102 ?

Thanks again for you help.
Cheers,
Micha

[Aaron_G]

Micha,

With you attempting to measure 120 VAC RMS, that means you expect a number of samples to be above 120 V which is above the point at which the module can measure the signal. Even with multiple samples, you will not be able to accurately determine the RMS voltage as the signal will be clipped. Unfortunately, there are no FieldPoint modules that currently exist that are intended for AC measurement at the voltages you desire.

Regards,
Aaron

[Relay 21]

Hi im tryin to measure ac voltage with my fieldpoint AI-102 but im having problems acquiring the signal, i want to get the sinusoid that im measure and get the data of the waveform and write it to a file, and  i dont know how to do it, could you give some tips ?

Thanks

regards

Phd Student
Luis Trujillo

[Kameralina]

Hello Luis,

The update rate on the AI-102 module is 360Hz, which means that you can only accurately acquire waveforms with frequencies below 180Hz. 
FieldPoint wasn't made for high speed measurements, so you will have to make sure that you are able to acquire the waveform you want to with the hardware that you have.

If you want to know how you would do the acquisition, I urge you to take a look at the LabVIEW shipping examples.
Help»Find Examples... and browse to Hardware Input and Output»FieldPoint»Analog IO

As for writing to the file, you can take a look at examples under Fundamentals»File Input and Output.  You can use the functions included in the Functions Palette under Programming»File I/O.

I hope that this helps!