Emc Compliance Of The Complete Installation; Placing The Brake Resistors; Protecting The System Against Thermal Overload; Protecting The Resistor Cable Against Short-Circuits - ABB ACS880-07 Hardware Manual

EMC compliance of the complete installation

Note: ABB has not verified that the EMC requirements are fulfilled with external user-
defined brake resistors and cabling. The EMC compliance of the complete installation
must be considered by the customer.

Placing the brake resistors

Install the resistors outside the drive in a place where they will cool.
Arrange the cooling of the resistor in a way that:
•
no danger of overheating is caused to the resistor or nearby materials
•
the temperature of the room the resistor is located in does not exceed the allowed
maximum.
Supply the resistor with cooling air/water according to the resistor manufacturer's
instructions.
WARNING! The materials near the brake resistor must be non-flammable. The
surface temperature of the resistor is high. Air flowing from the resistor is of
hundreds of degrees Celsius. If the exhaust vents are connected to a ventilation
system, ensure that the material withstands high temperatures. Protect the resistor against
contact.

Protecting the system against thermal overload


The brake chopper protects itself and the resistor cables against thermal overload when
the cables are dimensioned according to the nominal current of the drive. The drive control
program includes a resistor and resistor cable thermal protection function which can be
tuned by the user. See the firmware manual.
A main contactor is not required for protecting against resistor overheating when the
resistor is dimensioned according to the instructions and the internal brake chopper is in
use. The drive will disable power flow through the input bridge if the chopper remains
conductive in a fault situation but the charging resistor may fail.
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

DIx

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 of external brake resistors

All brake resistors must be installed outside the drive. Follow the resistor manufacturer's
instructions.
x
x
Resistor braking 225