3 Phase measurement with non transformer isolated supply

Discussion in 'The Projects Forum' started by themindflayer, Oct 29, 2010.

  1. themindflayer

    Thread Starter Member

    Oct 29, 2010
    44
    1
    Hi,
    This project is part of a larger power electronics project - power conditioning being done per phase. Which is working fine and produces notable HF noise ... which has been suppressed using RFI toroids, and LC Filters (to some extent)

    Now I am designing a single monitoring board to monitor each phase which will use SPI to transmit data btw uC on power conditioning board and a single uC on the monitoring board. Each phase has a distinct SMPS supply which produces +12V and +5V via 7805 being run off the said 12V.

    I do not want to make another supply and
    I wish to keep the noise being generated in one phase to NOT travel to the other ....
    I also want the monitoring board functioning even if 2 phases fail.

    The only conclusion I came to was use optos for data iso and use blocking diodes for i/p power to board.

    Given these 3 constraints I was wondering what other possible options do i have?

    Thanks
     
  2. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    8,754
    760
    Hey welcome mate.
    U have to use opto's for data.
    As for supply. It can be pretty simple. An SMPS on three phase bridge will suite ur needs

    Why don't you give us more details on what u are trying to do and also on what u already had done
     
  3. themindflayer

    Thread Starter Member

    Oct 29, 2010
    44
    1
    thanks for the feedback .. but my no 1 constraint is dont want to make another SMPS ... since that would entail bringing 3phase power lines onto my monitoring board which would lead to a bigger PCB due to isolation req's, added electronics for SMP another possible noise source ....

    further details on the project .... originally the project was power conditioning (something like this) for single phase .... after successfully doing single phase i extended to three phase using 3 individual boards ....

    each board had its own display board ..... with 3 phase being a 'single' unit i want a single display/monitoring board ....
     
  4. themindflayer

    Thread Starter Member

    Oct 29, 2010
    44
    1
    bump!

    more ideas needed .....
     
  5. Kermit2

    AAC Fanatic!

    Feb 5, 2010
    3,789
    945
    SLA batterys and a backup UPS circuit to switch ALL the SMPS's that lose power from their primary source to the battery backup. (since you use 12volts then you may not need anything but some relays and a watchdog circuit to switch) Good batteries kept in ready standby can last 10-15 years with regular maintenance and weather tight installation, if this device must operate outdoors, unattended.

    Selection of the battery size and power draw of the circuit in your programmed 'fail' mode will determine how many days or weeks of time you have till replacement. since it would only run when there was a loss of power then it could be checked when someone comes to make repairs, perhaps? You will probably have spare Watts aplenty in your SMPS's so you could recharge slowly with that if power is restored.

    Background: I use battery backup and solar panels for power failures along with a small gas genny, so I'm inclined to like them, since they have served my needs well for so long.

    Good luck with the project,
    Kermit
     
  6. themindflayer

    Thread Starter Member

    Oct 29, 2010
    44
    1
    posted in the wrong thread :(
     
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