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M54128 Earth Leakage Current Detector

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kevindd992002

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Can anyone please help me on what function does the M54128 Earth Leakage Current Detector do? I don't quite understand what it does based on the datasheet: http://www.datasheetcatalog.com/datasheets_pdf/M/5/4/1/M54128.shtml provided by Renesas/Mitsubishi.

I'm in the process of doing an Analysis and Simulation job in my company but I'm new to this. I have the circuit of the whole chip but am having a hard time analyzing it.

Any help would be much appreciated. Thanks.
 
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Go to Home Depot an buy a GFCI outlet. Disassemble it...
 
What does earth-leakage exactly mean? Is this unwanted current that flows to ground?

What mike is suggesting is to buy a GFCI outlet and take it apart. The theory being that current in is equal to current out and if current in does not equal current out the difference is going somewhere. So to answer the above quote, yes.

If the current in > the current out then the current has leakage to ground other than the normal current path. If this path is other than normal then we want to immediately stop all current flow as the path other than normal could be through a person. Thus we want to Interrupt the current.

A Google of GFCI will provide a wealth of information.

Also, your link is not very good.

Ron
 
The GFCI has a torroid with Hot and Neutral single turn loop wound in opposite directions creating equal but opposite fields in the torroid core (cancelling effect). The torroid also has a sense winding (many turns) that feeds into the detector/controller I.C.

If the hot line current does not exactly equal the neutral line current, there is some residual field signal that is picked up, amplifed, and detected by I.C.

They are pretty remarkable, able to detect 10 to 20 uA's of mis-match in hot to neutral lines with a hair drier drawing 10 amps. The leakage path being a path to ground through the person.
 
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Thanks for the info. Now I understand the function of the chip in a general sense. But I need to go in-depth looking into Transistor Level and to the expected input and output graphs presented in the datasheet.

Can you guys help me in analyzing how it works by explaining the graphs presented in page 6 of the datasheet of this chip?

Sorry for the wrong link, I've updated it already.
 
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The graphs show how the filtering works.

The earth leakage current needs to be over the threshold for a certain amount of time to trip the breaker. So when the current goes over the threshold, the voltage on the TRC1 or TRC2 pin starts to rise. When that rises to 2.4 V, the breaker is tripped.

Or something like that.
 
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