Braking Resistor Types; General System Design Items; Fuse Protection - ABB ACS850 Application Manual

32
The resistance R
•
according to the braking chopper data of the drive module in question.
The resistance value R
•
peak braking power requirements. In the following calculations, the value of U
840 V DC.
R
•
min(
Where P
The selected braking resistors should be able to handle the braking energy
•
generated in fast dynamic situations (time is just a few seconds).
•
Where E
rating of the concerned individual braking chopper.
The nominal power rating of the resistor must be adequate for the average
•
regenerative power.
•
Where P
continuous load). For more detailed analysis and more optimum selection, the pulse
load curves of the selected resistor should be studied.

Braking resistor types

Resistor types JBR-xx and SAFUR for dynamic load cycles are available for the drive
modules. See the relevant hardware manual for detailed data.

General system design items

Fuse protection

Fuses are needed on the AC supply side and in the DC connections. These provide
protection for the cabling and also limit the damages in case there is a short circuit in
the system. The following items should be checked for fuse selection:
fuse class depending on the fault current type and protected items
•
fuse voltage rating
•
fuse current rating
•
standards and regulations. The general guidelines for the fuse selection are given
•
here. Take always also the local and application specific regulations into account.
Common DC configurations
of each individual braking resistor must be at least R
br(i)
br(i)
< <
R
) i br
( ) i
( P
1
br , max
is the braking power rating of the concerned braking chopper.
br,max(i)
P
br , cont ( ) i
+ +
( P P ...)
1 2
br , cont br , cont
is the energy pulse rating of the individual resistor and P
R(i)
P
br , cont ( ) i
+ +
( P P ...)
1 2
br , cont br , cont
is the nominal power rating of the individual resistor (steady state
N,R(i)
of each individual braking resistor should also fulfil the
( )
2
U
dc
P
×
br , max( ) i
P
+ +
gen
P ...)
2
br , max
∫
× <
P dt E
gen R ( ) i
× <
P P
gen , ave N R , ( ) i
, max
br,cont(i)
br,min
is
dc
is the power