confusing about Rogowski coil measuring & calculating

[daffdaff]

Hi Everyone,

I've made the Rogowski coil for current pulse dectection, and it's able to work.

I have two questions.

1. How do I know the scale factor of my coil (mV/A) ?

2. If I use numerical integration (trapizoidal tool in Matlab) to integrate the output signal of the coil (data point from oscilloscope). The result is primary current already right?
( Vo=M(dI/dt) ---> I=(1/M)∫Idt ) or I still need to use scale factor of my coil (mV/A) ?

Thanks for answer.

 

[FvM]

The simple equation for Rogowski coil sensitivity can be found everywhere in literature, e.g. here https://en.wikipedia.org/wiki/Rogowski_coil

Rogowski coils is a dI/dt sensor, the scale factor must have a unit of V*s/A not V/A.

Multiplying the scale factor with the integrator "gain" 1/T gives the overall sensitivity.

 

[daffdaff]

Yes, the scale factor that you told is M (Vs/A) right? (multiple with dI/dt, we will get unit in Voltage). But, mine is not.
Rogowski coil is current transducer but it give the output in unit of voltage. So the scale factor that I mean is some factor that multiple with output of the coil(Voltage) = Current that it was measured (A)

 

[FvM]

There's no other "scale factor" than Rogowski coil sensitivity M.

But, mine is not.

Why?

 

[daffdaff]

From this link, You will see output sensitivity in mV/A
**broken link removed**

 

[daffdaff]

It is the commercial Rogowski coil fluike i6000s, and it has scale factor in unit of mV/A. It make me confuse with M (Vs/A)

 

[FvM]

The shown Rogowski coil sensor has a built-in integrator, thus it has mv/A scale factor (M/T).

 

[daffdaff]

Ohhh I get it. Thanks a lot, and I'm sorry to waste your time.

1. If I use numerical integration, the scale factor is only M.
2. If I use an external integrator, the scale factor is (M/T).

Is that correct?

For the second choice, How do I know the value of L or C of integrator, if I want the result to closely match shape with measured pulse.

 

[FvM]

The Rogowski sensor with built-in integrator basically derives the original current waveform. The instrument has upper and lower bandwidth limits given in the specification. The exact low frequency cut-off characteristic and related waveform deviations have to be determined empirically.