ABB ACS380 Hardware Manual page 132

132 Resistor braking
Equations for selecting the resistor:
Eq. 1. U = 200...240 V:
N
U = 380...415 V:
N
U = 415...480 V: R =
N
Eq. 2. E = P
Rpulse Rmax
Eq. 3. P = P
Rave Rmax
where
R = calculated brake resistor value (ohm). Make sure that: R
P = maximum power during the braking cycle (W)
Rmax
P = average power during the braking cycle (W)
Rave
E = energy conducted into the resistor during a single braking pulse (J)
Rpulse
t = length of the braking pulse (s)
on
T = length of the braking cycle (s).
WARNING! Do not use a brake resistor with a resistance below the minimum
value specified for the particular drive. The drive and the internal chopper are
not able to handle the overcurrent caused by the low resistance.
150000
R =
P
Rmax
450000
R =
P
Rmax
615000
P
Rmax
·
t
on
t
on
·
T
t
on
T
For conversion, use 1 hp = 746 W.
< R < R
min mxx
P
Rmax
P
Rave
.