ABB ACS880-34 User Manual

Resistor braking 235
1. The braking power of the custom duty cycle must not exceed the maximum braking
power given in the table under Brake choppers on page 232.
2. The braking energy transferred during any 600-seconds period must be less than or
equal to the energy that is transferred during the reference braking cycle of 40
seconds every 600 seconds:.
where
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 the maximum braking power (P
br,max
).
Example 2
The duration of a braking cycle (T) is three minutes. The braking time (t
br
) is 40 seconds.
Result: The maximum allowed braking power for the cycle is 50% of the rated value given
for the reference cycle.
 SAFUR resistors
The degree of protection of SAFUR resistors is IP00. The resistors are not UL listed. The
thermal time constant of the resistors is 555 seconds.
n Number of the braking pulses during the 600-second period
P
br
Braking power for the custom duty cycle in kW
t
br
Braking time within the custom duty cycle in seconds
P
br,max
Maximum braking power allowed for 40 seconds every 600 seconds. See the value in the
table under Brake choppers on page 232.
P
br
< P
br,max
n × P
br
× t
br
< P
br,max
× 60 s
P
br
<
P
br,max
x 60 s
3 x 40 s
= 0.5 x P
br,max
1.
2. P
br
< P
br,max
t
600 s
T t
br
P
br,max
P
br

ABB ACS880-34 Specifications

General

Brand	ABB
Model	ACS880-34
Category	DC Drives
Language	English