D-12 Parameter Reference 
AC30V series Variable Speed Drive 
Braking 
Parameters::Motor Control::Braking 
 
The braking function controls the rate at which energy from a regenerating motor is dumped into a resistive load. This dumping prevents the dc 
link voltage reaching levels which would cause an Overvoltage trip. 
 
PNO  Parameter Descriptions 
0249  Braking Enable 
Enables operation of the dynamic braking feature.  
0251  Brake Resistance 
The value of the dynamic braking load resistance. 
0252  Brake Rated Power 
The power that the load resistance may continually dissipate. 
0253  Brake Overrating 
Multiplier that may be applied to 
 for power overloads lasting no more than 1 second. 
0254  Braking Active 
A read-only parameter indicating the state of the brake switch. 
 
Functional Description 
When enabled, the Braking feature monitors the internal dc link voltage every milli-second and sets the state of the brake switch accordingly. 
 
The Braking feature provides a control signal that is used by the Slew Rate limit feature. This causes the setpoint to be temporarily frozen 
whenever the brake is operating because the dc link voltage exceeds the internal comparison level. This allows the stop rate to be automatically 
tuned to the characteristics of the load, motor, Drive and brake resistor. 
 
The Braking feature operates even when the motor output is not enabled. This allows the function to continually monitor the energy dumped into 
the braking resistor, and the energy dissipated across the brake switch. With this information the Drive is able to deduce the loading on the brake 
resistor. Optional trips may be enabled should the switch or resistor be loaded beyond its capabilities. 
 
The "Brake Resistor" and "Brake Switch" trips are disabled by default. To enable these trips, refer to Trips Status page D-121. When using  
braking, the brake resistor information must be entered and these two trips enabled.