Application Criteria - WEG CFW-09 User Manual

CHAPTER 7 - DIAGNOSTICS AND TROUBLESHOOTING

8.7.1 Application Criteria

264
The Line Reactor and the DC Bus Choke, when properly sized, have practically
the same efficiency in reducing the harmonic currents. The DC Bus Choke
has the advantage of not introducing a motor voltage drop, while the Line
Reactor is more efficient to attenuate power supply voltage transients.
DC Link Inductor equivalent to the line reactor is:
L
NOTE!
The 44 A to 79 A/500-600 V, 107 A to 472 A/500-690 V and 100 A to 428 A/
660-690 V models have a DC Link inductor built in the standard version. It is
not necessary to have minimum supply impedance or add external line
inductors for protecting these models.
The line reactor or the DC Link Inductor shall be applied when required
impedance is insufficient for limiting the input current peaks, thus preventing
damages to the CFW-09. The minimum required impedances, expressed as
impedance drop in percent are following:
a) For the model with rated current  130 A/220-230 V,  142 A/380-480 V or
 32 A/500-600 V: drop of 1 % for the line voltage;
b) For the model with rated current  180 A/380-480 V : drop of 2 % for the
line voltage;
c) For models with rated current  44 A/500-600 V or  107 A/500-690 V or 
100 A/660-690 V: there is no requirement for the minimum required line
impedance for the CFW-09 protection. These impedances are ensured by
the internal existing DC choke. The same is applicable when DC Link
inductor is incorporated into the product (Special Hardware - Code HC or
HV), in the models with currents  16 A/220-230 V or  13 A/380-480 V
and  240 A/380-480 V.
As an alternative criteria, a line reactor should be added when the inverter
supply transformer has a rated power higher than indicated below:
CFW-09 Rated Current/
volts
6 A to 28 A/220-230 V
3.6 A to 24 A/380-480 V
2.9 A to 14 A/500-600 V
45 A to 130 A/220-230 V
30 A to 142 A/380-480 V
22 A to 32 A/500-600 V
180 A to 600 A/380-480 V
Table 8.10 - Line reactor usage criteria
To determine the line reactor needed to obtain the desired voltage drop,
use equation below:
Voltage Drop [%] x Line Voltage [V]
L =
3 x 2
= L 3
X
-
DC EQUIVALENT AC
Transformer
Power [kVA]
125
5 X Inverter Rated Power
2 X Inverter Rated Power

Line Freq [Hz] x Rated Cur.[A]
[H]