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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 in a place where they will cool.
Arrange the cooling of the resistor in a way that:
•
no danger of overheating is causer 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. The 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.
Selecting the chopper enable input cable
Make sure that the cable connecting the resistor thermal switch to chopper enable input X1
meets the following requirements:
•
shielded cable
•
rated operating voltage between a core and ground > 750 (U
•
insulation test voltage > 2.5 kV.
Protecting the system against thermal overload
The drive control program includes a resistor and resistor cable thermal protection function,
which can be tuned by the user. The brake chopper protects itself and the resistor cables
against thermal overload, provided that the following conditions are met:
•
the resistor assembly is equipped with a thermal switch, which is connected to chopper
enable input X1
•
fault indication relay output X3 is wired to the main contactor circuit of the drive
•
the cables are dimensioned according to the nominal current of the drive.
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Operation principle
If the resistor overheats, its thermal switch opens and interrupts the chopper enable input
signal. The signal is internally wired to the chopper control board via a temperature sensitive
switch. Upon a fault, the relay output either opens the drive main circuit breaker or gives a
fault indication to the overriding control system, which takes care of the protection.
For more information on the thermal protection function, see the appropriate drive firmware
manual.
Planning the installation 27
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