￭ Selecting and routing the brake resistor cables
Use the same cable type for the resistor cabling as for the drive input cabling to ensure
that the input fuses also protect the resistor cable. Alternatively, a two conductor shielded
cable with the same cross-sectional area can be used.
Minimizing electromagnetic interference
Follow 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
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.
Resistor braking 265
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