Minimizing Electromagnetic Interference; Maximum Cable Length; Emc Compliance Of The Complete Installation; Placing The Brake Resistors - ABB ACS880-04 Hardware Manual

Minimizing electromagnetic interference

Obey these rules in order to minimize electromagnetic interference caused by the rapid
current changes in the resistor cables:
•
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 should be 0.3 meters.
•
Cross the other cables at right angles.
•
Keep the cable as short as possible in order to minimize the radiated emissions and
stress on chopper IGBTs. 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 length of the resistor cable(s) is 10 m (33 ft).

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 module 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.
Resistor braking 235