Maximum cable length
The maximum length of the resistor cable(s) is 50 m (164 ft).
￭
Selecting the installation location for the brake resistors
Protect the open (IP00) brake resistors against contact. Install the brake resistor in a
place where it cools 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 space that the resistor is in does not go above the allowed
maximum value.
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 brake 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. By
default, a brake chopper fault is wired to stop the supply unit of the drive.
Thermal protection of the resistors
The standard resistors available as option +D151 are equipped with a thermal switch.
The switches of the resistors are wired in series and connected to the Enable input of
the brake chopper. The relay output of the chopper is wired to the supply control unit
so that a chopper fault condition stops the supply unit.
With custom resistors, user must implement a similar protection. Use cable rated as
follows:
• twisted pair, shielding recommended
• rated operating voltage between a conductor and ground (
U
0
) > 750 V
• insulation test voltage > 2.5 kV.
Keep the cable as short as possible.
￭
Protecting the resistor cable against short-circuits
The input fuses of the drive will also protect the resistor cable provided that the
resistor cable is of the same type as the input cable.
Mechanical installation of custom brake resistors
Obey the resistor manufacturer’s instructions.
Resistor braking 339
To Next Page
Loading...
