Rockwell Automation Allen-Bradley 1305-AA02A, Руководство по установке

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Power Distribution 2-5
AC Line Impedance To prevent excess current that may damage drives during events such as line
disturbances or certain types of ground faults, drives should have a
minimum amount of impedance in front of them. In many installations, this
impedance comes from the supply transformer and the supply cables. In
certain cases, an additional transformer or reactor is recommended. If any of
the following conditions exist, serious consideration should be given to
adding impedance (line reactor or transformer) in front of the drive:
A. Installation site has switched power factor correction capacitors.
B. Installation site has lightning strikes or voltage spikes in excess of
6000V Peak.
C. Installation site has power interruptions or voltage dips in excess of
200VAC.
D. The transformer is too large in comparison to the drive. See impedance
recommendation tables Table 2.A on page 7 through Table 2.H on
page 13 that are specific to each drive.
Using these tables will allow the
largest transformer size for each product and rating based on
specific differences in construction, and is the preferred method to
follow.
Otherwise, use one of the two following more conservative methods:
1. For drives without built-in inductors, add line impedance whenever the
transformer kVA is more than 10 times larger than the drive kVA, or the
percent source impedance relative to each drive is less than 0.5%.
2. For drives with built-in inductors, add line impedance whenever the
transformer kVA is more than 20 times larger than the drive kVA, or the
percent source impedance relative to each drive is less than 0.25%.
To identify drives with built-in inductors, see the product specific tables.
The shaded rows identify products ratings without built-in inductors.
Use the following equations to calculate the impedance of the drive and
transformer:
Drive Impedance (in ohms)
Z
drive
V
line line
–
3 I
input rating –
⋅
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