3-terminal regulator IC protection

[metebalci]

Hi,

I am trying to build a three-terminal IC based high voltage regulator. There are such circuits below in datasheets (the one below is from TL783 from TI) for short-circuit protection. Since the base of protection transistor (here it is TIP150 darlington) is at 120V when output is shorted, the three-terminal device always see about 120V between its terminal. Moreover, (input voltage - 120V) is Vce of TIP150. Is it correct ?

Does putting a low voltage zener (15V maybe if TL783 is permitted to work at 15V differential) work as long as rated voltage of transistor is more than 200V-15V=185V ?

Is there any other considerations that must be taken into account to select transistor ? (beta etc.)

When using such a circuit for a plate supply of a tube amplifier, is it required to protect the regulator from short-circuit ? Is there any possibility (except accidents) to plate to be shorted to ground by a transformer or tube failure ?

Do you prefer to use IC-based regulator or discrete regulator for high voltage regulation ?

Thanks so much...

MB