ABB ACS880-34, Руководство по оборудованию

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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