Measuring Current

Willyham · Post by **Willyham** » Wed Mar 28, 2007 6:40 pm

Using a PicoScope 3204 I'm finding it difficult to get a good looking current measurement. Because the default mode is volts I've tried creating a custom range. The result is almost a perfect rectangular shape which appears to be overvoltage (warning icon appears). I have tried inputting the table so that the ranges are beyond the signal's voltage input range but still the result appears over-voltage.
Any possible solutions?

Post by **alan** » Thu Mar 29, 2007 6:30 am

Hi,

Please can you give us details of the current clamp or dropping resistor you are using to measure current (ie is the output 1mV per amp)?

Next its best to do a reality check and just display the waveform on the scope using a normal voltage range.

Please then post the details of the scaling you are using - for example if the scaling should be 1mV per amp and you want to measure 0 to 100A the the scaling would be

0 0
100 100

If you also want negative current (-100A to 100A) then use

-100 100
0 0
100 100

Regards
Alan

Willyham · Post by **Willyham** » Fri Mar 30, 2007 7:34 pm

Looks like I was using V to A scaling when should have been using the mV to A scaling. That fixed the problem. Thanks !

Carl Grotti · Post by **Carl Grotti** » Sun Apr 01, 2007 5:19 pm

For clarification, I think Alan meant the -100A to 100A range should look like this provided your high current probe is outputting 1mV/AMP.

-100 -100
100 100

Regards,
Carl

Post by **alan** » Mon Apr 02, 2007 9:51 am

Thanks Carl! I am obviously not qualified yet to help on the Forum!

Alan

Carl Grotti · Post by **Carl Grotti** » Tue Apr 03, 2007 1:46 am

You're welcome, Alan.

Hey, don't cut yourself short. You're doing a good job helping others. I just happen to know ranging very well and thought it would be a good idea to make sure our users have it right. I personally would like to see this same ranging in PS 6, but I understand the justification in that it helps avoiding an entry that is wrong.

Once again, you're doing ok Alan. It is easy to make a typo.

Best Regards,
Carl