Baumuller b maxx BM4400, Instruction Handbook Manual

Page: 227 / 360

Operation
Instruction handbook b maXX BM4400, BM4600, BM4700
Document No.: 5.12008.07
227
of 358
8
8.3.4 Calculation of the maximum permitted external capacity
If a maximum allowable external capacity is specified in the technical characteristics, then
it is either a device with diode rectification or one with the „old“ charge circuit (time con-
trolled charging). If, however, it is referred on this chapter the maximum external DC link
capacity is calculated as followed prescribed.
The time for a charge sequence depends on the height of the charging current pulses and
also the height of the internal and external capacity (see
Z Table of charging times – on
page 228). After 20 seconds the charging is discontinued.
For the charging function the device must be connected to a power supply with clockwise
rotating field. No charging is started in case of counterclockwise rotating field. In rare cas-
es a counterclockwise rotating field can cause an abrupt charging and a tripped fuse.
No charging is started at failure of one or two mains phases.
The external chargeable capacity is not limited because the height of the loading current
of the DC link capacitor is approx. constant. But the time until the complete charge of the
DC link is increased proportional to the capacity, that has to be charged. Error 089 („pow-
er unit not ready-to-operate“ is generated, if the charging is not finished after 20 s.
Example: BM4443 on 480 V.
From Z Table of charging times – on page 228 results a charge time of 0.4 s with the built
in capacity of 1880 µF.
It is recommended to choose the external capacity 20 % lower, because the charging
time can vary depending on the height of the power supply voltage.
HINWEIS!
Please check first if it is a device with the old charge circuit (see Z Page 226 – ).
Should it be such a device of the sizes 3 to 6, then it is to consider that the maximum
permitted capacity on the DC link (device internal capacity plus external capacity) has
not to be larger than 20 mF.
Maximum external capacity built in capacity
20s
Charging time according table
------------------------------------------------------------------------------- 1 –
 
 

=
1880µF
20s
0.4 s
------------ 1 –
 
 

92mF = =