Three Multiplus in independent "three-phase operation"

Hello, I would like to discuss an idea for server-room setup:

  • Currently the server room is feed by 3 phase (with one N)
  • If the main fails, a generator kicks in and with a transfer switch it’s hand over from main to generator
  • I would like to replace the generator and transfer switch with 3x independant Multiplus-Setup for each phase (battery, cerbo GX, multiplus II 5000/8000)
  • why idenpendant and not as configured 3-phase-system: Out of my opinion it is more fail-safe. If on thing fails, it has only effects on one phase
  • Main-power from AC-in (L1-N, L2-N, L3-N - common N)
  • Out to the consumers: AC-out 1 (L1-N, L2-N, L3-N - common N)

Main question: Does this work? Problems I see:

  • The phases are not 120° shifted.
    • worst case (=0°) the current on N = *3 ← based on the current capcity of installation this is not an issue
    • no 3-phase consumers are connected; all are 1 phase. Most components (server/switch) use 2x 1phase
  • From my understanding the MP checks, if the PEN is closed on the output (AC-out 1). If yes, it does not start the “island operation”
    • What happens, if one of the MP is faster than the others: It will start the “island operation” and closes internal the PEN.
    • The next MP sees a closed PEN and does not start the “island operation”.
    • Am I wrong or is there a way to close the PEN-relay but do not check it?

Is there another showstopper?

Thank you and best,
Johannes

Hi i think its possible, but over complicated and expensive,

in 3 phase setup you can turn off switch as group, so if one multiplus fails the others still run

if designed right it should run for years without problems