Help me Identify this component by ST

[CrazyTiger]

Hi,

I have this diode by ST which is shorted as someone fed 240AC to the 24v DC line.



I believe its a bidirectional TVS diode, the marking is BEX. Can anyone suggest what would be the part number for this.
 My first guess is it might be SM15T39CA.
https://www.st.com/resource/en/datasheet/sm15t.pdf

Is there any other possibility?

[fzabkar]

It looks correct, but I'm wondering why the designer didn't choose a 24V unidirectional diode, assuming it is connected across a regulated 24VDC supply. A bidirectional diode affords no real reverse polarity protection, and a 40V breakdown voltage might be too high for the circuit.