Planning the braking system
￭ Selecting the brake circuit components
Selecting the default brake system components
1. Calculate the maximum power generated by the motor during braking.
2. Select a suitable drive, brake chopper and brake resistor combination for the application
from the brake ratings table below. The braking power of the chopper must be greater
than or equal to the maximum power generated by the motor during the braking.
3. Make sure that the resistor selection is correct: The energy generated by the motor
during a 400-second period must not exceed the resistor heat dissipation capacity E
R
.
Note: If the E
R
value is not sufficient, it is possible to use a four-resistor assembly in
which two standard resistors are connected in parallel, two in series. The E
R
value of
the four-resistor assembly is four times the value specified for the standard resistor.
Selecting a custom brake resistor
If you use other than ABB resistor,
1. make sure that the resistance of the custom resistor is greater than or equal to the
resistance of the default ABB resistor.
where
Resistance of the custom resistor
R
WARNING!
Never use a brake resistor with a resistance smaller than R
min
. The drive and the
chopper are not able to handle the overcurrent caused by the small resistance.
Resistance of the default resistor
R
min
WARNING!
Never use a brake resistor with a resistance smaller than R
min
. This will cause
overcurrent that will damage the brake chopper and the drive.
2. make sure that the resistance of the custom resistor does not restrict the braking capability
needed, ie.
where
Maximum power generated by the motor during braking
P
max
Drive intermediate DC circuit voltage.
1.35 · 1.2 · 415 V DC (when supply voltage is 380 to 415 V AC)
1.35 · 1.2 · 500 V DC (when supply voltage is 440 to 500 V AC) or
1.35 · 1.2 · 690 V DC (when supply voltage is 525 to 690 AC)
U
DC
Resistance of the custom resistor
R
262 Resistor braking
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