Well, one of the 5 cards on the board cannot be tripped up because you have the trips, so there are 4 cards left that can give your opponent a set, thus, the odds of your opponent holding a PP (about 1/2, dunno the exact) * (1 - the odds of none of those 4 cards giving him a set) =

.5 * (1 - (47/49 * 46/48 * 45/47 * 44/46)) = 7.91%

This is assuming your set is the lowest set on the board.

Second lowest - 6%
Mid - 4%
Second highest - 2%

So at worst you're 92% to win if no draws are showing and nobody pulls a boat or overpair trips out of their nuggets. Trips should be well slowplayed or bet to snot, always, fear only the obvious draw.





As an additional bonus, I have prepared a poorly mathed chart to see if your PP is beaten by a higher PP preflop (assuming 50% chance of opponent's PP)
KK: 3.8%
QQ: 7.7%
JJ: 11.5%
TT: 15.4%
99: 19.2%
88: 23.1%
77: 26.9%
66: 30.8%
55: 34.6%
44: 38.5%
33: 42.3%
22: ~48%