ABB ACS880-04 drive modules - Brake Chopper Selection Formulas; Brake Resistor Selection Formulas - System with One Brake Chopper

28 Planning – basics
Brake chopper selection formulas
Use these formulas to select the choppers and verify the selection:
P
br,cont
> P
gen,ave
P
br,max
> P
gen,max
P
br,cont
= P
br,cont1
+ 0.8 × (P
br,cont2
+ P
br,cont3
+…)
P
br,max
= P
br,max1
+ 0.7 × (P
br,max2
+ P
br,max3
+…)
Brake resistor selection formulas - system with one brake chopper
Use these formulas to select the brake resistor, and to verify the resistor selection:
P
gen,ave
Average generating power of the common DC link. See DC link duty cycle diagram on
page 19.
P
gen,max
Maximum generating power of the common DC link. See DC link duty cycle diagram on
page 19.
P
br,cont
Continuous braking power of the common DC link. The braking is continuous if the braking
time exceeds 30 seconds.
P
br,max
Maximum braking power of the common DC link. Choppers withstand this braking power for
5 second within every minute.
P
br,cont1
Continuous braking power of the chopper 1. See section Brake chopper power ratings on
page 44.
P
br,max1
Maximum braking power of the chopper 1. See section Brake chopper power ratings on
page 44.
E
r
Energy pulse that the resistor can withstand and dissipate during a predefined period. See
the drive hardware manual (ABB brake resistors) or resistor data sheet.
P
g1
Generating power of the common DC link during time t
g1
. See t
g1
and the graph in section
Defining the energy absorbing capacity of the common DC link on page 22.
P
gen
(t) Generating power of the common DC link as a function of time over one duty cycle.
P
gen,max
Maximum generating power of the common DC link.
P
N,r
Nominal power of the brake resistor
R
br
Resistance of the brake resistor
R
min
Minimum resistance of the brake resistor that you can use with the drive. See the drive
hardware manual.
t
g1
Duration for generating power P
g1
. See the graph in section Defining the energy absorbing
capacity of the common DC link on page 22.
U
ac
AC power line voltage
U
dc,h
= 2.1 × U
ac
(high DC link voltage value but clearly below the trip level)
R
br
> R
min
R
br
<
U
dc,h
P
gen,max
2
E
r
> ʃP
gen
(t) ×dt = Σ((P
g1
× t
1
) + … + (P
gn
× t
n
))
P
N,r
> P
gen,ave