Rockwell Automation 1336_S_F_T Allen-Bradley Dynamic Braking - Manual (Page 12)

Heavy Duty Dynamic Braking 12
1336-5.64 — July, 2005
If the line you drew lies to the left of the constant temperature power curve
of the Dynamic Brake Resistor, then there will be no application problem.
If any portion of the line lies to the right of the constant temperature power
curve of the Dynamic Brake Resistor, then there is an application problem.
The application problem is that the Dynamic Brake Resistor is exceeding
its rated temperature during the interval that the transient power curve is to
the right of the resistor power curve capacity. It would be prudent to parallel
another Dynamic Brake Module or apply a Brake Chopper Module with a
separate Dynamic Brake Resistor.
ATTENTION: The heavy duty dynamic brake unit contains a
thermostat to guard against overheating and component damage.
If the thermostat sensed excessive ambient temperature
associated with a high duty cycle, torque setting, or overload
condition, the thermostat will open and disable the brake until
components cool to rated temperature. During the cooling period,
no brake operation is available.
If reduced braking torque represents a potential hazard to
personnel, auxiliary stopping methods must be considered in the
machine and/or control circuit design.
!