Protecting The Resistor Cable Against Short-Circuits - ABB ACS880-07 Hardware Manual

254 Resistor braking
Note: If an external brake chopper (outside the drive module) is used, a main contactor is
always required.
A thermal switch (standard in ABB resistors) is required for safety reasons. The thermal
switch cable must be shielded and may not be longer than the resistor cable. Wire the
switch to a digital input on the drive control unit as shown in the figure below.
+24VD
Θ
DIx

Protecting the resistor cable against short-circuits


The input fuses of the drive will also protect the resistor cable provided that the resistor
cable is of the same type as the input cable.
Mechanical installation of custom brake resistors
All brake resistors must be installed outside the drive. Obey the resistor manufacturer's
instructions.
Electrical installation of custom brake resistors
Checking the insulation of the assembly

Follow the instructions given under
Connection diagram

See section Connection diagram
Connection procedure

WARNING! Obey the instructions in chapter
ignore them, injury or death, or damage to the equipment can occur.
•
Do the steps in section
instructions before you start the work.
•
Connect the resistor cables to the R+ and R- terminals in the same way as the other
power cables. If a shielded three-conductor cable is used, cut the third conductor.
Ground the twisted shield of the cable (protective earth conductor of the resistor
assembly) at both ends.
•
Connect the thermal switch of the brake resistor as described in section
brake system against thermal overload
Brake system start-up
Note: New brake resistors may be coated with storage grease. As the brake chopper
operates for the first time, the grease burns off and may produce some smoke. Make sure
there is proper ventilation.
x
x
Custom brake resistor assembly
on page 107.
Precautions before electrical work
on page 253.
on page 100.
Safety instructions. If you
in chapter Safety
Protecting the