Current Transformer Bandwidth

[Napdiddy]

Hey guys,

I was just wondering what to take into consideration when I am looking at the bandwidth perspective of choosing a CT.

 

[davidbeach]

How do you anticipate using it that you'd even be concerned about bandwidth?

 

[Noway2]

To me this seems like it would be more of an issue with pulse or isolation transformers than current transformers. In any case, I would look up the concept of volt-seconds which impacts transformer saturation and ability to pass signal edges.

 

[RyreInc]

The core material can also important. Not sure on the details, but I know that some cores are better suited to unipolar pulses.

 

[DRWeig]

Since the OP hasn't told us the application, it's hard to say.

Just in case he's thinking of the motor side of a VFD, here's some prior work:

http://www.eng-tips.com/viewthread.cfm?qid=178369

Best to you,

Goober Dave

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[Napdiddy]

Sorry guys I got caught up with a lot of school work. I need to choose a CT that I can use to measure the THD up to the 51st harmonic of household appliances.

 

[Napdiddy]

I will be taking the measurements and will be inputting them into a DAQ, and will be displaying the THD in LabVIEW.

 

[dpc]

For standard power system CTs, response should be pretty good up through 50th harmonic. I looked into this several years ago. There are some seminal IEEE papers by D.A. Douglass that cover frequency response of CT and PTs.

 

[VEBill]

It's something that should be very easy to test / measure using simple test equipment. Then, one should be able to calibrate out any response curve. This is assuming that the CT doesn't go totally 'deaf' at such low kHz (seems unlikely).

Good luck.

 

[Noway2]

I think you are going to face bigger challenges than the CT. What level of attenuation are you looking at with the 51st harmonic? In other words, will you have enough signal to measure with your equipment? Will interference from other sources like you power supply be problematic? I assume you are planning on using an FFT for this, do you have a sufficient number of clean samples to get sufficient bin resolution? Things like that become real problems in physical applications that aren't apparent in simulations.