Rockwell Automation 1336 8A-48A Fiber Industry - Manual (Page 12)

2–4 Installation/Wiring
In general, the 1336 PLUS is suitable for direct connection to a
correct voltage AC line that has a minimum impedance of 1% (3%
for 0.37-22 kW/0.5-30 HP drives) relative to the rated drive input
kVA. If the line has a lower impedance, a line reactor or isolation
transformer must be added before the drive to increase line
impedance. If the line impedance is too low, transient voltage spikes
or interruptions can create excessive current spikes that will cause
nuisance input fuse blowing, overvoltage faults and may cause
damage to the drive power structure.
The basic rules for determining if a line reactor or isolation
transformer is required are as follows:
1. If the AC source experiences frequent power outages or
significant voltage transients, users should calculate the kVA
max
(see formula below). If the source transformer kVA exceeds the
calculated kVA
max
and the drive is installed close to the source, it
is an indication that there may be enough energy behind these
voltage transients to cause nuisance input fuse blowing,
overvoltage faults or drive power structure damage. In these
cases, a line reactor or isolation transformer should be considered.
Z
drive
(
Ω/Φ
) =
V
line–line
√
3 x Input Amps
(V
line–line
) 2 x % Source Leakage (5-6% typical)
Z
drive
x 0.01
kVA
max
=
2. If the AC source does not have a neutral or one phase referenced
to ground (see Unbalanced Distribution Systems on page 2–3),
an isolation transformer with the neutral of the secondary
grounded is highly recommended. If the line-to-ground voltages
on any phase can exceed 125% of the nominal line-to-line
voltage, an isolation transformer with the neutral of the secondary
grounded, is highly recommended.
3. If the AC line supplying the drive has power factor correction
capacitors that are switched in and out, an isolation transformer or
5% line reactor is recommended between the drive and
capacitors. If the capacitors are permanently connected and not
switched, the general rules above apply.
Refer to Unbalanced Distribution Systems on page 2–3.
!
ATTENTION: The 1336 PLUS does not provide
input power short circuit fusing. Specifications for the
recommended fuse size and type to provide drive input
power protection against short circuits are provided.
Branch circuit breakers or disconnect switches cannot
provide this level of protection for drive components.
Input Power Conditioning
Input Fusing