I want to measure three phase ac parameters such as voltage, current power factor, etc which daq device will serve the purpose.

[321hanan]

my task is to find out the daq devices that can measure 3 phase or single phase currents and voltages. We will use transducers or ct's and pt's if required to measure high values. Kindly suggest about the device.

[321hanan]

my task is to find out the daq devices(and thier minimum ranges) that can measure three or single phase paremeters. We will use ct's and ptsor other transducers if required for large values. Kindly name those devices that can serve the purpose. Thanks.  

[johnsold]

For simple measurements almost any device with enough channels and voltage ranges which match your PTs, CTs, and transducers should work. Since you want to calculate power factor you need enough samples on every cycle to get good phase resolution. So the maximum sampling rate of the device should be greater than the number of channels*power line frequency*phase error factor.  The phase error factor determines how many samples in each cycle of the fundamental power line frequency you need to take to get an acceptable error. For example suppose a 10 degree error was allowed. Then 360 degrees/10 degrees = 36 samples per cycle = phase error factor. Any value larger than this may be used.

The inexpensive devices do not have truly simultaneous sampling so there will be a slight phase shift between the channels. For what it seems you are trying to do this should not be a significant problem. It is a deterministic error so you can measure it and compensate if necessary.

Lynn

[StevenHowell]

321hanan,

If you are looking for a hardware solution, I would suggest a cSeries chassis with the NI 9225 to measure voltages (capable up to 300Vrms), and then the NI9227 for the current measurements (capable of up to 5A) you would likely need a current clamp or shunt for that. These two modules would fit nicely into an NI9174 4 slot chassis. 

This is actually a solution that is used quite often for power measurements. (It is not a "cheap" solution, but I equate "cheap" to low quality.)

Steven Howell

Certified LabVIEW Developer

LabVIEW Consultant

Arcus Technology Services, LLC.

steven.howell@arcustechservices.com