Calculating The Maximum Braking Power (Pbr) - ABB ACS880-37 Hardware Manual

Calculating the maximum braking power (P
•
Braking energy transferred during any ten minute period must be less than or equal to
the energy transferred during the reference braking cycle.
•
The braking power must not exceed the rated maximum value P
1. n × P × t
br
2. P < P
br brmax
n = Number of braking pulses during a 10-minute period
P = Maximum allowed braking power (kW)
br
t = Braking time (s)
br
P = Maximum braking power for a reference cycle (kW)
brmax
Example 1
The duration of a braking cycle is 30 minutes. The braking time is 15 minutes.
Result: If the braking time exceeds 10 minutes, the braking is considered continuous. The
allowed continuous braking power is 10% of maximum braking power (P
Example 2
The duration of a braking cycle (T) is three minutes. The braking time (t
P
brmax
1. P <
br
P
br
P
brmax
2. P < P
br brmax
Result: The maximum allowed braking power for the cycle is 37% of the rated value given
for the reference cycle.
< P × 60 s
br brmax
x 60 s
= 0.375 x P
4 x 40 s
T t
br
OK
)
br
brmax
t
600 s
Resistor braking 239
.
brmax
).
brmax
) is 40 seconds.
br