Analog input to DAQ6009

[Okoye]

Hi,

I am trying to do a project based on LabVIEW and it requires Daq6009 to be interfaced with a 3 phase induction motor. The Daq has 8 analog inputs and I can't figure out whether the analog input has to be ac or dc?

Since I am interfacing AC motor, should I convert the ac supply to a suitable dc value in order to give it as an input or can I just step down the value and give it as a voltage?

Please help me out!

Thanking you,

Abigail 

[justgene]

first of all what are you trying to measure/control on that 3 phase motor?  A 3 phase motor runs on 3 phase AC somewhere around 220 or 440 volts! Not suitable for direct connections of any kind so be careful!

[Okoye]

Hi Justgene ,

I am trying to conduct a power quality analysis on the 3 phase induction motor by developing a virtual instrument with LabVIEW. The voltage is around 415V and I was going to step it down to a very low value in order to connect it to Daq6009. What I am not sure about is whether I have to convert this stepped down voltage to DC ?? Can I just step it down and connect this ac signal directly to daq ?? 

[justgene]

You can measure AC and DC with the analog inputs, but the range is +/- 10 v max.  I guess you know the various formula for computing the power of a 3 phase system? Also, there are devices on the market that are used for measuring (by reducing the potentials involved) the power and current which you could use to interface with your NI equipment.

Good luck

Gene

[Okoye]

 Hi Gene,

Thank you! So I can step it down and connect to my Daq 6009, right? I was hoping to use a voltage and current transducer( LV25P and LA55P). Is that what you meant by the last line?

[justgene]

I'm not familiar with the devices you mention, but yes just reduce the levels to comply with the operating parameters of the 6009's max value limits. Don't forget to restore the lower levels measured by multiplying the measured values by the reduction factor.  In other words if you reduce the 415 Vac voltage by a factor 100 resulting in a measurement of 4.15 Vac you have to multiply the measured value by 100 to display (or calculate) the correct values.

Gene