PM8240 Current G RMS and calculation

[Chiragshah]

Can you please confirm what is "Current G RMS" value being shown on the webpage of PM8240 meter.

I believe it is Ground fault current value. 

what is the formula used to calculate the "Current G RMS" value.

Webpage screen attached.

[Charles_Murison · Accepted solution]

Hello @Chiragshah 
Have a look at https://digital-energy-help.se.com/pm8000/en-us/content/02-commissioning/residual-current-measuremen...

Regards,

Charles

[Sreejith_KM · Accepted solution]

Hi @Chiragshah 

Assuming 4CT connection, where (I4) is used to measure current flow (In) in the neutral conductor, the meter refers to residual current as ground current (Ig), which is calculated value.

For 4-wire Wye systems, ground current is calculated as the difference between the measured neutral current and the vector sum of all measured phase currents.

This was in the case of PM5K and assume same for PM8K also. Hope someone can revalidate this.

[DanL · Accepted solution]

The PM8240 default web pages do not contain the exact label "Current G RMS", so I suspect you are looking at a web-page for an external software package and not at the meter's webpage (PME?). I've attached a screenshot of the meter's default web page (viewed in any browser pointed to the meter's IP address).

The "Current G RMS" is showing the value of the "I5" output register... which as other posts have mentioned is the meter's RMS calculation of measured residual current on I1, I2, I3, and I4.

The four measured current inputs have instantaneous samples of each added together to create the residual current waveform.

For a 4-wire system with 4 CTs wired to all 4 inputs of the meter, the residual current (aka. I5, aka "Current G") will be the current flowing through ground (or some path that is not on the 4 wires).

Please confirm that this meter is installed with 4 CTs on a 4 wire system (most likely based on readings provided). The programmed CT ratios will also be useful to understand the signal levels.

[Chiragshah]

Thank you team for your answer. @DanL i will get back to you with detail asked. As of now it is clear to me.

[Nhabombe]

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