26
Braking resistor selection
Resistor(s) should be selected according to regenerative power
requirements. The following conditions must be fulfilled.
Single braking resistor
• The resistance must be at least R
br,min
according to braking chopper
data of the ACSM1 drive module
• The selected resistance value R
br
should also fulfil the peak braking
power requirements. In the following calculations the value of U
dc
is
840V DC.
•
,maxgen
dc
brmin
P
U
RR
2
<<
• The selected braking resistor should be able to handle the braking
energy generated in fast dynamic situations (time is just few seconds).
•
Rgen
EdtP <
where E
R
is the energy pulse rating of the selected resistor.
• The nominal power rating of the resistor must be adequate for the
average regenerative power.
•
R,Nave,gen
PP <
where P
N,R
is the nominal power rating of resistor (steady state
continuous load). For more detailed analysis (and more optimum
selection) the pulse load curves of the selected resistor should be
studied.
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