Resistor braking
223
Calculating the maximum braking power (P
br
)
• 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
brmax
.
Example 1
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
brmax
).
Example 2
Duration of a braking cycle is three minutes. The braking time is
40 seconds.
Result: The maximum allowed braking power for the cycle is 37 % of the rated value
given for the reference cycle.
n × P
br
× t
br
< P
brmax
× 60 s
n = Number of braking pulses during
a ten minute period
P
br
= Maximum allowed braking power (kW).
t
br
= Braking time (s)
P
brmax
= Maximum Braking Power
for a reference cycle (kW)
P
br
< P
brmax
1.
2.
P
brmax
t
P
br
600 s
P
br
<
P
brmax
× 60 s
4 × 40 s
= 0.375 × P
brmax
t
br
T = Duration of braking cycle
1.
2. P
br
< P
brmax
O.K.
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