Protecting The System In Brake Circuit Fault Situations - ABB ACS560 Hardware Manual

186 Resistor braking
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 physical contact.

Protecting the system in brake circuit fault situations

Protecting the system in cable and brake resistor short-circuitsituations
The input fuses will also protect the resistor cable when it is identical with the
input cable.
Protecting the system against thermal overload
Equipping the drive with a main contactor is highly recommended for safety
reasons. Wire the contactor so that it opens in case the resistor overheats. This
is essential for safety since the drive will not otherwise be able to interrupt the
main supply if the chopper remains conductive in a fault situation. An example
wiring diagram is shown below. We recommend that you use resistors equipped
with a thermal switch (1) inside the resistor assembly. The switch indicates
overtemperature and overload.
We recommend that you also wire the thermal switch to a digital input of the drive.