Rockwell Automation 1336R REGEN LINE REG - Manual (Page 21)

Regenerative DC Bus Supply Operation 2–5
380-480VAC Power
Wiring Unbalanced Distribution Systems
The 1336 REGEN Package is designed to operate on 3Ø 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 equipment. Where
this potential exists, an isolation transformer with the neutral of
the secondary grounded, is strongly recommended.
Ungrounded Distribution Systems
All precharge units are equipped with MOVs (Metal Oxide
Varistors) that provide voltage surge protection plus
phase-to-phase and phase-to-ground protection 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
line-to-line and line-to-ground voltage ratings listed in the
Specifications may cause physical damage to the MOV.
Figure 2.2 — Ungrounded Distribution System
1 2 3 4
Joules = (B)
Ground
Three-Phase
AC Input
T (L3)
S (L2)
R (L1)
Joules = (A)
Joules = (A)
Joules = (A)
Line-to-Line MOV Rating
Energy Rating = 2 x Line-to-Line Rating (A)
= 2 x 140
= 280 Joules
Line-to-Ground MOV Rating
Energy Rating = Line-to-Line (A) + Line-Ground (B)
= 140 + 220
= 360 Joules