R
min
The minimum permitted resistance value of the brake resistor
Selecting and routing the brake resistor cables
Use a shielded cable specified in the technical data.
￭
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.
￭
Maximum cable length
The maximum length of the resistor cable(s) is 10 m (33 ft).
Placing the brake resistors
Install the resistor assembly outside the drive in a place where it is able to cool
effectively.
Arrange the cooling of the resistor so that:
• no danger of overheating is caused to the resistor or nearby materials, and
• the temperature of the room the resistor is located in does not exceed the
allowed maximum.
Supply the resistor with cooling air or coolant according to the resistor
manufacturer’s instructions.
138 Resistor braking
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