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Hello,

I have a little question about the CS11 sensor. I get quantity of the same king of magnet (CR8448-2500-N instead of the CS11 CR8459-2000-N) but, in order to use them properly, I must know what are the exact resistor added in the CS11 documentation scheme :

https://drive.google.com/file/d/1y2MPETHb68r78xbujrrBLqwLm-JEz621/view?usp=sharing

There is 3 resistors, the first could be the internal magnet resistor should be 73 ohm accroding to the original documentation.

But it could be another adding of Campbell., don't really know.

In any case I must know what are the other resistors too.

Could you please detail on it ? I could buy a CS11 and disassemble it but, I prefer not too !

Thanks,bye

Hello,

well, it takes more time alone but I'm learning ; The 3 resistors scheme seem to be dedicated in a CR200 use, because this datalogger doesn't have reading when current is reverse (sinusoidal regime). So With a CR800 it could be not necessary.

So I used the CR8448 instead of a CR8459 and applied these formulas :

The CR8448 have 2500 windings (unlike the CR8459 which have 2000 windings). In my measured circuit, as I have very low current (~1A), I made 5 passes of the measured wire into the CR8448 sensor. And, I put a 10 ohm burden resistor just like de CS11.

i1*n1 = i2*n2 ; i2 = i1*(n1/n2) = 1*(5/2500) = 0,002 ; so for a measured circuit through which a current flows of 1 Amp, the sensor have a current of 2 mA.

And, with the burden resistor :

U = R*I ; 10*0,002 = 20mV ; so the multiplier to use into the program to convert Amp in the measured circuit, to calculated Amp on the datalogger is 0,08.

By calculating apparent, active and reactive power, my 50 Watt power resistor seem using 50,49 Watt, so it seem calculation is correct.

I'll testing it on other devices, to check it.

Bye

And here my prog, by the way.

I just take it from the documentation, I'm not familiar with StdDevSpa function, but it works !

Note : I put this initial CR1000 prog into a CR800 and compiling works, I hope this is correctly interpreted by it. 

'CR1000 program to measure rms current

PipeLineMode 'must be pipeline mode
Const num_samples = 100 '100 Samples @ 1000 micro sec = 0.1 second (5 @ 50Hz or 6 @ 60 Hz).
Public Amps 'the line current
Public Amp_mult
Dim i_sig (num_samples) 'to hold the burst measurements, each 100 samples long
PreserveVariables 'to store values between power cycles

DataTable (AmpTable,True,-1)
    DataInterval (0,1,Min,10)
    Maximum (1,Amps,IEEE4,False,False)
    Average (1,Amps,FP2,False)
EndTable

BeginProg
    ' CR8448 DCR is 134 ohms (no need)
    ' 10 Ohms burden resistor
    ' 5 winding of the measured circuit
    ' 2500 winding into the sensor
    ' i2=i1*(n1/n2) ; i2=1*(5/2500)=0,002 ; for 1A in the circuit, 2mA in the sensor
    ' With the burden resistor : U = R*I = 10*0,002 = 0,02 V / 20mV
    ' For 1A in the circuit, 20mV read.
    ' so multiplier is 0,08 to convert Amp mesured into mV read 
  Amp_mult = 0.08
  Scan (250, mSec, 10, 0)
    VoltSe (i_sig (1), num_samples, mV2500,-2, True, 1000, 0, 1.0, 0)
    StdDevSpa (Amps, num_samples, i_sig (1))
    Amps = Amps * Amp_mult 'put in amps
    CallTable (AmpTable)
  NextScan
EndProg

This post is under review.