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3 phase 3 wire measurement

Thread starter #1
Dear all,

I am trying to build 3 phase voltmeter that could measure L-L and L-N voltage during 3 phase 3 wire and 3 phase 4 wire connection. 3 phase 3 wire and 3 phase 4 wire connection are external connection.

as we know in 3 phase 4 wire we will get neutral reference so we can get accurate reading for L-L and L-N.
but in case of 3 phase 3 wire we dont have neutral reference .In this case it will be difficult to get gnd reference. I would like use both connection type in common circuit,

I have seen one of the product where they using V-X-M-H IC , can some one suggest me functionality of this iC. i have attached schematic for reference.

If any other suggestion with schematic will be appreciated. to differentiate 3 phase 3 wire and 3 phase 4 wire


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Well-Known Member
Most Helpful Member
Can you just use some suitable resistors in a star formation to make a virtual neutral?

Thread starter #3
Dear sir,

I have attached some of circuit used and tested . I need help in to complete isolation and grounding part to MCU,
How can do this using differential amplifier circuit.
Circuit 1: purely based on voltage divider network and for delta connection. I wanted to use common circuit for both star and delta. how can i isolated the ground here.

Circuit 2: Using V-X_m_H ic OR TA1G label printed on it. i am curious to know what this ic will do??


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