NI9263 AC Output and Power measurement

[HangXu]

I try to use NI9263 (Analogue output) to generate AC output to the amplifier. The output voltage of the amplifier is measured by NI 9242 (Voltage input) directly.  The output current of the amplifier is measured by the current clamp and the current clamp is connected with NI9215 (Voltage input) to convert the measured voltage to current results. However, I have two problems right now.

1. If I want to change the output amplitude after running the Labview code, it will wait for around half-minute to respond as shown in the attached figures. How can I solve the delay of the output response?

2. Another problem is the calculation of the value of active power. I use the Electrical power toolkit to calculate the power by measure the output voltage and output current. The measurement of apparent power is correct. However, the active power and power factor change each time when I restart the LabVIEW, and sometimes the active power is negative. Obviously, it is not correct. Does the phase problem is caused by the current clamp or the LabVIEW code?

[DanC12]

Hi HangXu, 

I'm not sure if your current clamp is working correctly or not, but an alternative way to measure the current using you NI 9215 is to follow this: https://knowledge.ni.com/KnowledgeArticleDetails?id=kA00Z0000019MDJSA2&l=en-GB, essentially using a known resistor and measuring the voltage across it, then using Ohms Law in LabVIEW to solve for current. 

For the LabVIEW code, its worth checking a couple of things:

1.  Maybe have your voltage output in a seperate while loop, maybe theres a delay here somewhere which interferes with the output. Have a look at the DAQ examples included with LabVIEW as this change should be quicker than 30 seconds. 
   1. DO you have a real oscilloscope or DMM to see if the output is delayed, or if its the input modules?
2. Double check the maths (multiplying the output of the current measurement by 10) as I don't know if this is correct.