990-91380K-001

Notes on Interconnected Inverter Midpoint in Existing 3-Wire Parallel Systems

Some existing 3-wire parallel systems have the inverter midpoint of each UPS interconnected by cable in a daisy chain configuration. This is not relevant for new installations. It is possible to remove the daisy chained inverter midpoint from existing installations. Removal requires a full shutdown of the UPS system and mandatory recommissioning and start-up by Schneider Electric. Contact Schneider Electric for details.

DANGER
Hazard of electric shock, explosion, or arc flash
  • Hard-wired inverter midpoint between the UPS systems is energized even when the UPS is isolated from the parallel system and completely shut down.
  • Even if absence of voltage is measured, there can still be dangerous voltage transients on the neutral busbar.
  • Entering the I/O terminal area requires full shutdown of the entire parallel system and transfer to maintenance bypass.
Failure to follow these instructions will result in death or serious injury.
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