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ADE5569 AC voltage measurement and DC supply grounding

Question asked by saimot on Apr 23, 2014
Latest reply on Apr 29, 2014 by hmani

Hello,

 

Im going to measure single AC line voltage (230V) using ADE5569. MCU is currently on a breadboard and is supplied with lab DC power supply. When DC supply is disconnected from the circuit and AC voltage is connected to ADE according to datasheet is seems OK. However, when DC is connect to the circuit residual-current device (RCD) disconnects the AC line.

 

According to UG-061 there is a direct connection of AC NEUTRAL to DC 0V (fig.9 R25).

 

So what might cause the problem?

 

Does it mean that the AC NEUTRAL and DC 0V are not on the same voltage level? So there was a current flowing from AC NEUTRAL to DC 0V and then to DC supply EARTH, or opposite? That would explain RCD action(current was not returning through phase but but through EARTH).

 

The same will happen when the serial line is connected to the ADE circuit. What seems to help is using supply that does not have EARTH connected. However connection to PC would still need isolation.

Can anyone explain what exactly is happening when connecting both DC supply/PC and AC line?

 

Thank you for advice,

 

Tomas

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