Arduino and several SCT-013-000 sensors

Submitted by mel on Sat, 18/07/2015 - 18:14

How is it possible to connect several SCT-013-000 sensors?

I have tried this sketch

#include "EmonLib.h"
EnergyMonitor emon0;
EnergyMonitor emon1;
EnergyMonitor emon2;    

void setup()
{  
  Serial.begin(9600);
  emon0.current(0, 67);
  emon1.current(1, 67);
  emon2.current(2, 67);
}

void loop()
{
  double Irms0 = emon0.calcIrms(1480);
  double Irms1 = emon1.calcIrms(1480);
  double Irms2 = emon2.calcIrms(1480);

  Serial.println((Irms0-0.25)*230.0);    
  Serial.println((Irms1-0.25)*230.0);
  Serial.println((Irms2-0.25)*230.0);  
  Serial.println("------------------------ ");
}

Is it correct?

Re: Arduino and several SCT-013-000 sensors

Submitted by mel on Sat, 18/07/2015 - 18:18.

Results with disconnected sensors looks like

------------------------
3.26
3795.58
30.77
------------------------
62.61
2692.00
10.27
------------------------
10.45
2346.02
57.11
------------------------

Re: Arduino and several SCT-013-000 sensors

Submitted by mel on Sat, 18/07/2015 - 18:54.

Solved!

The problem was in disconnected burden resistor

Re: Arduino and several SCT-013-000 sensors

Submitted by Robert Wall on Sat, 18/07/2015 - 19:03.

With no burden resistor, the CT output is high and meaningless. There's a picture of the waveform in the report on the CT in Building Blocks.

Although the SCT-013-000 CT is relatively safe without a burden resistor, that is not the case for CTs generally and you can have high and lethal voltages from a large CT should the burden become disconnected. A CT is always safe if it is short-circuited, but potentially dangerous and can be irreparably damaged if open-circuited.

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