The Braking transistor is inbuilt in maximum ratings of Altivar 71 Drive.
The following Altivar 71 Drive ranges ATV71HpppM3, ATV71HpppM3X, ATV71H075N4…HC16N4, ATV71WpppN4, ATV71PpppN4Z and ATV71HU22Y…HC16Y have a built-in dynamic brake transistor.
However for the following Altivar 71 Drive ranges ATV71HC20N4…HC50N4 and ATV71HC20Y…HC63Y a braking unit must be used. This is controlled by the Drive.
Refer attachment for the Braking Unit Part reference details.