Shunt braking resistor

Summit series devices allow using shunt braking resistors to dissipate the regenerative energy on the DC bus.

The systems consist of a braking resistor, typically external to the drive, and a power transistor that is activated when the DC bus value exceeds a certain value. For some drivers the shunt transistor is internal, on others like Everest, the transistor must be added externally or on an interface board. In this case, a general-purpose output can be configured to enable the shunt braking transistor.

The shunt algorithm enables the assigned pin when the drive's bus voltage exceeds the shunt enable voltage. The pin stays active until the bus voltage decreases below the shunt disable voltage.

Internal shunt braking resistor configuration

The internal shunt uses hardware already implemented in the summit device. This feature might not be available on all drives, depends on the hardware. 

External shunt braking resistor configuration

The external shunt can be mapped to one or several digital outputs. Those outputs should activate the braking transistor. This can be done directly connecting the output to the transistor gate (when using low power, logic-level threshold transistors) or activating a gate driver when a high power transistor is necessary. 

External shunt braking resistor output mapping

External shunt needs to be mapped to a general-purpose output in order to work. It can be mapped to several outputs simultaneously. The general-purpose output mapping parameters can be found in the Inputs and outputs section.