Hardware Manual

Resistor braking 247
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.
 Protecting the resistor cable against short-circuits
The input fuses will also protect the resistor cable when it is identical with the input
cable.
Mechanical installation
All brake resistors must be installed outside the drive. Follow the resistor
manufacturer’s instructions.
Electrical installation
 Checking the insulation of the assembly
Follow the instructions given under Brake resistor assembly on page 88.
 Connection diagram
See section Connection diagram on page 90.
 Connection procedure
• 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, insulate it, and 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 above in section
Frames R1 to R4 or Frames R5 to R9.
Start-up
Note: Protective oil on the brake resistors will burn off when the brake resistor is used
for the first time. Make sure that the airflow is sufficient.

+24VD x
DIx x