All heavy isolation movments kill my elbows. When I first started training I could french press and close grip press a ton of weight, but as the years went by I think all those heavy isolation movments wore my elbows out. I only do one exercise for triceps these days, dips. My tri's take a beating from all of the overhead pressing I do anyway.
I also wonder if you are warming up enough before your heavy sets?
My only advice would be:
1. Warm up
2. Pre-exhaust your triceps with heavy compound movments like bench presses or shoulder presses.
3. Lighten the load on isolation movements.
4. Ice your elbows after training to get rid of any inflamation.
I hope that helps a bit.