EMC compliance of the complete installation
ABB cannot test that the EMC requirements are fulfilled with custom brake resistors
and cabling. The customer must consider the EMC compliance of the complete
installation.
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.
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,
make sure that the material withstands high temperatures. Protect the resistor
against contact.
￭ Protecting the system in fault situations
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, ABB always
requires a main contactor.
￭ Selecting the default brake system components
1. Calculate the maximum power generated by the motor during braking.
2. Select a suitable drive, brake chopper and brake resistor combination for the
application from the brake ratings table in the technical data. The braking power
of the chopper must be greater than or equal to the maximum power generated
by the motor during the braking.
3. Make sure that the resistor selection is correct: The energy generated by the motor
during a 400-second period must not exceed the resistor heat dissipation capacity
E
R
.
Note: If the
E
R
value is not sufficient, it is possible to use a four-resistor assembly
in which two standard resistors are connected in parallel, two in series. The
E
R
value of the four-resistor assembly is four times the value specified for the
standard resistor.
￭ Calculation example
Drive: ACS580-04-04-585A-4. Maximum continuous braking power (
P
brcont
) of the
internal brake chopper is 315 kW. Preselected ABB resistor is 2×SAFUR200F500. Braking
Resistor braking 243
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