Selecting The Brake Resistor; Selecting And Routing The Brake Resistor Cables; Minimizing Electromagnetic Interference; Maximum Cable Length - ABB ACS880-104 Hardware Manual

Selecting the brake resistor


The ratings table (page 331) lists an example brake resistor for each inverter type. These
resistors are available from ABB.
When sourcing a resistor from a third party, make sure that:
1. The resistance of the custom resistor is greater or equal than the minimum allowed
resistance:
R > R
min
where
R Resistance of the custom resistor.
R Minimum allowed resistance of the brake resistor. See
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 DC link voltage by the
chopper:
2
U
DC
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) or
1.35 · 1.25 · 500 V DC (when supply voltage is 440 to 500 V AC)
R Resistance of the custom resistor

Selecting and routing the brake resistor cables


Use the same cable type for resistor as for inverter input cabling to ensure that the inverter
DC fuses also protect the resistor cable.

Minimizing electromagnetic interference

Follow these rules in order to minimize electromagnetic interference caused by the rapid
current changes in the resistor cable.
•
Shield the braking power line completely, either by using shielded cable or a metallic
enclosure. Unshielded single-core cable can only be used if it is routed inside a
cabinet that efficiently suppresses the radiated emissions.
•
Install the cables away from other cable routes.
•
Avoid long parallel runs with other cables. The minimum parallel cabling separation
distance is 0.3 meters (1 ft).
•
Cross other cables at right angles.
•
Keep the cable as short as possible. The longer the cable, the higher the radiated
emissions, inductive load, and voltage peaks over the IGBT semiconductors of the
brake chopper.

Maximum cable length

The maximum cable length of the resistor cable is 10 m (33 ft).
Resistor braking using frame R1i...R4i inverter modules 327
WARNING! Never use a brake resistor with a resistance smaller than R
inverter module and the chopper are not able to handle the overcurrent caused by
the low resistance.
Ratings (page 331).
. The
min