ABB ACH480 - Page 218

2. Calculate resistance R with Equation 1.
3. Calculate energy E
Rpulse
with Equation 2.
4. Select the resistor so that the following conditions are met:
• The rated power of the resistor must be greater than or equal to P
Rmax
.
• Resistance R must be between R
min
and R
max
given in the table for the used
drive type.
• The resistor must be able to dissipate energy E
Rpulse
during the braking
cycle T .
Equations for selecting the resistor:
Equation 1
When the drive supply voltage is 200 ... 240 V:
When the drive supply voltage is 380 … 415 V:
When the drive supply voltage is 415 ... 480 V:
Equation 2
Equation 3
t
on
P
Rmax
P
Rave
T
For conversion, use 1 hp = 746 W.
R Calculated brake resistor value (ohm). Make sure that: R
min
< R < R
max
P
Rmax
Maximum power during the braking cycle (W)
P
Rave
Average power during the braking cycle (W)
E
Rpulse
Energy conducted into the resistor during a single braking pulse (J)
t
on
Braking time (one cycle) (s)
T Braking cycle time (s)
218 Resistor braking