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.
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
Brake resistors must be installed outside the drive. Obey the resistor manufacturer’s
instructions.
Electrical installation
￭ Measuring the insulation of the assembly
See section Measuring the insulation of the brake resistor circuit (page 91)
￭ Connection diagram
See section Connection diagram (page 92).
￭ 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.
Resistor braking 267
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