WEG CFW-11 RB - Page 36

3
Installation and Connection
3-16 | CFW-11 RB
Table 3.3: Values of the constants for sizing the pre-charge
Model k
E
k
T
CFW110142T2O...RB... 0.0030 0.0180
CFW110180T2O...RB... 0.0053 0.0315
CFW110211T2O...RB... 0.0053 0.0315
CFW110105T4O...RB... 0.0030 0.0180
CFW110142T4O...RB... 0.0030 0.0180
CFW110180T4O...RB... 0.0053 0.0315
CFW110211T4O...RB... 0.0053 0.0315
CFW110242T4O...RB... 0.0094 0.0564
CFW110312T4O...RB... 0.0118 0.0705
CFW110370T4O...RB... 0.0141 0.0846
CFW110477T4O...RB... 0.0188 0.1128
CFW110515T4O...RB... 0.0235 0.1410
CFW110601T4O...RB... 0.0235 0.1410
CFW110720T4O...RB... 0.0329 0.1974
CFW110760T4O...RB... 0.0329 0.1974
CFW110053T6O...RB... 0.0010 0.0060
CFW110063T6O...RB... 0.0010 0.0060
CFW110079T6O...RB... 0.0015 0.0090
CFW110107T6O...RB... 0.0020 0.0120
CFW110125T6O...RB... 0.0025 0.0150
CFW110150T6O...RB... 0.0025 0.0150
CFW110170T6O...RB... 0.0063 0.0376
CFW110216T6O...RB... 0.0063 0.0376
CFW110289T6O...RB... 0.0078 0.0470
CFW110315T6O...RB... 0.0094 0.0564
CFW110365T6O...RB... 0.0125 0.0752
CFW110435T6O...RB... 0.0125 0.0752
CFW110472T6O...RB... 0.0125 0.0752
Example:
In a drive composed of a BRCFW110601T4ORBZ as regenerative converter and a BRCFW110601T4ODCZ as
output inverter, whose line voltage in the converter input is 380 VRMS, the obtained values would be the following:
 For this model, the kE value is 0.024. Thus, the energy stored in the in capacitor bank is: 0.024.(380)
2
= 3466 J.
 Using three 10 Ω resistors (one per phase), each resistor must withstand 1155 J.
 The manufacturer of the resistor can inform the energy the component withstands.
 The peak current during the pre-charge is 0.83. (380) /10 = 31.54 A.
 For this model, the kT value is 0.141. Thus, the duration of the pre-charge is 0.141x10 = 1.41 s.