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ADE7758 voltage reading hangs on contactor swtching...

Dear Friends ,

  I have an application where i am using Two ADE7758 to measure 3 phase voltages for Mains , Generator etc.Both channels are different and are fed with isolated supplies of 5V dc.

SInce in the design The neutral is made common to the ground.I am facing the following issue:

In the System when the contactor switches on/off to pass different phases of mains and/or dg .The Voltage reading on the display freezes for a phase . Sometimes it sticks to zero and doesnt rise ,and sometime it freezes to last hold value say 235V and doesnt go to zero even if the source is at 0 v AC.

If we remove the supply of the Ic ade7758 and apply again ,The reading becomes correct.

Please suggest what could be the possible solution to this.and Plz elaborate any possible causes.

  • On further investigation we found that , The problem is there even if we give voltage voltage by variacs instead of contactor switching.....

    The Communication is taking place between uc and Ade7758 via an isolator ADUM2401.

    I can read the data from the Ade7758 , but the data becomes abruptly high (AVRMS) .And it remains there until we power on the ic again.I guess SOme malfunction at the IC end .Please suggest what could be the issue.....for hanging .

  • Hai. I am also having same problem. Are you able to solve this?

  • Hi ,  i Just saw your message .yes i was able to solve it .Major issue was with the serial communication . Kindly use oscilloscope to check the proper signals . Most of the times the problem resolves when you are able to see what commands you are sending and what the ic is sending back in response. The waveforms gives you best clarity.

  • Hello! Can you please share some more details about the solution that you have found? We are probably facing the same problem, but it is extremely hard to replicate (happens very rarely) so also hard to investigate. I'm pretty sure the SPI communication in my case is correct, because MCU can read all other registers with no issues, all of them including the checksum - no error reported, the values are reasonable. Except the values of voltage, which get extremely high, and currents, which get extremely low (however the checksum still matches...) - to get the readouts back to normal we have to do a software reset of the ADE7758 but it has some drawbacks which we would prefer to avoid, also this just masks the problem instead of fixing it.

    Thanks in advance!