5-4 Electrical Installation
Rockwell Automation Publication 22C-IN002E-EN-P - November 2010
Observe these guidelines when installing an isolation transformer:
• A power disconnecting device must be installed between the power line
and the primary of the transformer.
• If the user-installed power disconnecting device is a circuit breaker, the
circuit breaker trip rating must be coordinated with the in-rush current
(10 to 12 times full load current) of the transformer.
• Do not use an input isolation transformer rated more than 1000 kVA for
480 V AC (500 kVA for 208V AC) with less than 5% impedance
directly ahead of the drive without additional impedance between the
drive and the transformer.
Table 5.B
shows recommended inductance and line reactor ratings.
Table 5.B AC Line Reactors
Installing Fuses for Branch Circuit Protection
If they were not installed as a factory option, install the required branch
circuit protection fuses according to the applicable local, national, and
international codes (such as NEC/CEC). The fuses must be installed in the
line before the drive input terminals.
Drive (Hp) Line Reactor Inductance (±10%)
2…3 6.5 mH
5 3.0 mH
7.5 2.5 mH
10 1.5 mH
15 1.2 mH
20 0.8 mH
25 0.8 mH
30 0.7 mH
40 0.5 mH
50 to 60 0.4 mH
75 0.3 mH
100 0.2 mH
125 0.15 mH
150 0.11 mH
ATTENTION: Most codes require that upstream branch
protection be provided to protect input power wiring. Failure to
observe this precaution could result in severe bodily injury or
loss of life.
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