Rockwell Automation 20D PowerFlex 700S with Phase I Control Reference Manual - Manual (Page 176)

176 Rockwell Automation Publication PFLEX-RM002D-EN-E - August 2013
Chapter 1 Detail Drive Configuration and Operation
Unbalanced or Ungrounded
Distribution Systems Unbalanced Distribution Systems
This drive is designed to operate on three-phase supply systems whose line
voltages are symmetrical. Surge suppression devices are included to protect the
drive from lightning induced overvoltages between line and ground. Where the
potential exists for abnormally high phase-to-ground voltages (in excess of 125%
of nominal), or where the supply ground is tied to another system or equipment
that could cause the ground potential to vary with operation, suitable isolation is
required for the drive. Where this potential exists, an isolation transformer is
strongly recommended.
Ungrounded Distribution Systems
All drives are equipped with an MOV (Metal Oxide Varistor) that provides
voltage surge protection and phase-to-phase plus phase-to-ground protection
which is designed to meet IEEE 587. The MOV circuit is designed for surge
suppression only (transient line protection), not continuous operation.
With ungrounded distribution systems, the phase-to-ground MOV connection
could become a continuous current path to ground. Energy ratings are listed
below. Exceeding the published phase-to-phase or phase-to-ground energy
ratings may cause physical damage to the MOV.
PowerFlex drives contain protective MOVs and common mode capacitors that
are referenced to ground. To guard against drive damage, these devices should be
disconnected if the drive is installed on an ungrounded distribution system where
the line-to-ground voltages on any phase could exceed 125% of the nominal line-
to-line voltage. Refer to your PowerFlex User Manual, 20D-UM001, for details.
1 2 3 4
Joules (J)
Ground
Three-Phase
AC Input
T
S
R
Joules (J)
Joules (J)
Joules (J)
Device Rating (V AC)
Phase-Phase Total
Phase-Ground Total
240/480 600
280J 320J
360J 410J
240 480/600
160J 320J
220J 380J
240/480 600
280J 300J
360J 370J
Phase-to-Phase MOV Rating
Includes 2 Phase-Phase MOVs
Phase-to-Ground MOV Rating
Includes Phase-Phase & Phase-Ground MOVs