[SOLVED] Measuring leakage current of mains using Current transformer

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Mrunal Ahirrao

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Hello everyone,
I am trying to measure leakage current using current transformer.I am using this circuit **broken link removed**
And instead of LM324 I am using OP07. But when I try to leak current the transformer don't respond to any leakage. maybe my leaking curent method is wrong. Experts please guide. I am attaching detailed schematic of my method.
 

If your Neutral is also very well earthed, you don't get a difference current by this method, just an additional load current.
Click to expand...
If the "leakage" resistor is connected between earth ground and phase, as indicated in the schematic, it will generate about 23 mA residual current with 230 V mains voltage which should be well detectable with a correctly designed sense amplifier.
 

chuckey said:
For a better test, connect your 10K to the incoming neutral and not "the wall". If its a well insulated wall then the leakage current could be microamps.
Frank
Click to expand...

Hi frank,
If I connect in that way then, that cannot be called leakage current as the current would go to neutral which won't make any inbalance in currents.

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FvM said:
If the "leakage" resistor is connected between earth ground and phase, as indicated in the schematic, it will generate about 23 mA residual current with 230 V mains voltage which should be well detectable with a correctly designed sense amplifier.
Click to expand...

Yes but there is no output from amplifier. And the circuit I have attached link of is good? I have set it for gain of 100

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erikl said:
If your Neutral is also very well earthed, you don't get a difference current by this method, just an additional load current.
Click to expand...

So how should I leak current?
 

If I connect in that way then, that cannot be called leakage current as the current would go to neutral which won't make any inbalance in currents.
Click to expand...
Review the test circuit of an industry standard RCD device, it's usually printed on the case. The resistor is connected between phase (after the CT) and N (before the CT), or as Frank said "incoming neutral", so it generates a perfect test current.

Yes but there is no output from amplifier. And the circuit I have attached link of is good? I have set it for gain of 100
Click to expand...
Lack of information. What's the shunt resistor value? Which CT type, is it high permeability CT core? Number of secondary turns? If all parameters are correct, there can be still a circuit fault,

It should be also no problem to check the sensor with higher AC currents.
 

Burden resistor is 10 ohms and CT type is unknown but its high sensitive with 7ma minimum with 525 secondary turns. And I have checked it to measure current in usual way and its working. But not when sensing leakage current.
 

I have tried putting the resistor terminal(that I am touching to Wall) to direct Earth and now I am seeing some "voltage" at the output of amplifier but its too low. As frank suggested it maybe microamps. Now I will change the amplifier gain to 500 an see again.
 

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