Selecting A Custom Resistor; Selecting And Routing The External Brake Resistor Cables - ABB ACS880-04 Hardware Manual

234 Resistor braking
which two standard resistors are connected in parallel, two in series. The E
the four-resistor assembly is four times the value specified for the standard resistor.

Selecting a custom resistor


If you use a resistor other than the default resistor, make sure that:
1. The resistance of the custom resistor is greater or equal than the resistance of the
default resistor in the rating table on page 237:
R > R
min
where
R Resistance of the custom resistor.
R Resistance of the default resistor
min
2. The load capacity of the custom resistor is higher than the instantaneous maximum
power consumption of the resistor when it is connected to the drive DC link voltage by
the chopper:
U
P >
r
R
where
P Load capacity of the custom resistor
r
U Drive DC link voltage.
DC
1.35 · 1.25 · 415 V DC (when supply voltage is 380 to 415 V AC)
1.35 · 1.25 · 500 V DC (when supply voltage is 440 to 500 V AC) or
1.35 · 1.25 · 690 V DC (when supply voltage is 525 to 690 AC)
R Resistance of the custom resistor

Selecting and routing the external brake resistor cables


Use the same cable type for the resistor cabling as for the drive input cabling to ensure
that the input fuses also protect the resistor cable. Alternatively, a two conductor shielded
cable with the same cross-sectional area can be used.
WARNING! Never use a brake resistor with a resistance smaller than R
The drive and the chopper are not able to handle the overcurrent caused by
the low resistance.
2
DC
value of
R
.
min