NOTICE
Risk of improper electrical connection of three-phase input power. Can cause backward
compressor rotation and unit damage. Service technicians should use a gauge set on the
system during the initial start up to verify that the three-phase power is connected properly.
The EC fans are not a reliable indicator of proper connection. The blowers will rotate the same
direction, regardless of the three-phase power input. Three-phase power must be connected
to the unit line voltage terminals in the proper sequence so that the compressors rotate in the
proper direction. Incoming power must be properly phased to prevent compressors from
running backward. We recommend checking the unit’s phasing with proper instrumentation to
ensure that power connections were made correctly. We also recommend verifying discharge
and suction pressures during start up to ensure that the compressors are running in the
correct direction.
NOTICE
Risk of improper electrical supply connection. Can cause equipment damage.
See transformer label for primary tap connections. Installer will need to change transformer
primary taps if applied unit voltage is other than pre-wired tap voltage.
NOTE: Unit Input Power Requirements: For three-phase units, only three power wires and an earth
ground are required. A neutral is not required at the unit input connections. See Wye- and Delta-
connected Power Supply for PDX and PCW below for detailed information.
The electrical connections are described in the submittal documents included in the Submittal Drawings
on page106.
The following table lists the relevant documents by number and title.
Document Number Title
DPN002933 Electrical Field Connections, Upflow & Downflow Models
DPN002934 Electrical Field Connections, Downflow Models
DPN002935 Electrical Field Connections, Upflow Models
DPN003266 PDX CANbus & Interlock Connections between PDX Unit & Liebert MC Condenser
DPN002169 Liebert MCCondenser Electrical Field Connections Premium Efficiency Control
Table 6.1 Electrical Field-connection Drawings
6.1 Wye- and Delta-connected Power Supply for PDX and PCW
Table 6.2 on the facing page shows the acceptable and un-acceptable power supplies by model number
for 208-V to 575-V nominal units. See Electrical Field Connections, for the electrical-connection locations
on the units.
Vertiv | Liebert® PDX™ and PCW™ Installer/User Guide | 52
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