How To Select The Correct Drive/Chopper/Resistor Combination - ABB ACS800-04 Hardware Manual

132 Resistor braking
How to select the correct drive/chopper/resistor
combination
1. Calculate the maximum power
2. Select a suitable drive / brake chopper / brake resistor combination for the
application according to the following tables (take account of other factors in
the drive selection also). The following condition must be met:
P > P
brcont max
where
P
denotes
br
3. Check the resistor selection. The energy generated by the motor during a 400-
second period must not exceed the resistor heat dissipation capacity
E
If the value is not sufficient, it is possible to use a four-resistor assembly in
R
which two standard resistors are connected in parallel, two in series. The
value of the four-resistor assembly is four times the value specified for the
standard resistor.
A resistor other than the standard resistor can be used provided that:
•
its resistance is not lower than the resistance of the standard resistor.
WARNING! Never use a brake resistor with a resistance below the value
specified for the particular drive / brake chopper / resistor combination.
The drive and the chopper are not able to handle the overcurrent caused by
the low resistance.
•
the resistance does not restrict the braking capacity needed, that is,
2
U
DC
P
max <
R
where
P
maximum power generated by the motor during braking
max
U
voltage over the resistor during braking, for example,
DC
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 V AC).
R resistor resistance (ohm)
•
the heat dissipation capacity
above).
(P
max
P P P P
, , ,
br5 br10 br30 br60
(E
) is sufficient for the application (see step 3
R
) generated by the motor during braking.
P
, or depending on the duty cycle.
brcont
E
.
R
E
R