Help Identify this part please

[EEEinator]

its the black chip in the middle with a big T on it with the little heatsink on it

The circuits its used in is to dim a light bulb in a microscope, the bulb is 125v AC, 30W

i need to find a replacement

Thanks

 

[Resqueline]

I don't know what part number that is, but it is an ordinary mains rated Triac. Just about any Triac made will do there.