ABB ACS580-04 - Protecting the System against Thermal Overload; Resistor Cables; Resistor Thermal Switch

Resistor cables
Cable type
Use the same cable type for the resistor cabling as for the drive input cabling or,
alternatively, a two conductor shielded cable with the same cross-sectional area.
Maximum cable length
The maximum length of the resistor cable(s) is 10 m (33 ft).
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 is 0.3 meters (1 ft).
• Cross the other cables at 90 degree 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 greater the radiated
emissions, inductive load and voltage peaks over the IGBT semiconductors of the
brake chopper.
Note: ABB has not verified that the EMC requirements are fulfilled with custom brake
resistors and cabling. The customer must consider the EMC compliance of the complete
installation.
Protecting the resistor cable against short-circuits
The input fuses of the drive will also protect the resistor cable when it is identical with
the input cable.
Resistor thermal switch
Use a resistor with a thermal switch (standard in ABB resistors).
Make sure that the cable in the resistor thermal switch circuit meets the following
requirements:
• shielded cable
• rated operating voltage between a core and ground > 750 ( U
0
)
• insulation test voltage > 2.5 kV
• jacket material for at least 90 °C (194 °F). Take into account further requirements
due to resistor construction and temperature.
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 overload protection function which can be
tuned by the user. See the firmware manual.
242 Resistor braking