3–10
Regenerative Brake Operation
380-480VAC Power
Wiring
Unbalanced Distribution Systems
The 1336 REGEN Line Regeneration Package is designed to
operate on 3Ø systems 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 3.3 — 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
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