Interpreting current probe output

Thread Starter

Peceman

Joined Nov 24, 2018
2
Hi all,

I've measured a phase current of BLDC using Fluke i310s current probe and oscilloscope, but now I'm having trouble converting the current probe output to an actual current through the phase. Before the measurement, the probe was adjusted to zero and set to the 300 A range with 1 mV/A. The probe attenuation set in the scope is 10, the vertical scale is 0.1 V. How do I convert the value of 0.6 measured on the oscilloscope channel to the current?

Somehow my interpretation of the current isn't what I expect it to be, therefore I'd like to verify this with you.
Thank you.
 

KeithWalker

Joined Jul 10, 2017
2,350
Hi all,

I've measured a phase current of BLDC using Fluke i310s current probe and oscilloscope, but now I'm having trouble converting the current probe output to an actual current through the phase. Before the measurement, the probe was adjusted to zero and set to the 300 A range with 1 mV/A. The probe attenuation set in the scope is 10, the vertical scale is 0.1 V. How do I convert the value of 0.6 measured on the oscilloscope channel to the current?

Somehow my interpretation of the current isn't what I expect it to be, therefore I'd like to verify this with you.
Thank you.
What is the frequency and shape of the waveform driving your BLDC?
The bandwidth of your probe is 1KHZ so you are probably trying to measure something way out of it's spec limits.
 

ronsimpson

Joined Oct 7, 2019
2,054
Somehow my interpretation of the current isn't what I expect
I use a "old light bulb" or a heater as a load to test a current probe. (do not use a LED bulb)
A resistive load like a 1000W heater or 100W bulb makes good load but a TV set or computer is a very bad load.
First do a "sanity" check. I have some 250W heat lamps for an example.
It is likely you are 10:1 off in your readings. (scope problem) or 2:1 off (some probes need a 50 ohm load at the scope).
 
Top