Any given muscle can only contract, or relax.
The triceps muscle is responsible for extention at the elbow, as it flexes, it extends the arm from a 90 degree angle to form a straight (180 degree) line. Triceps involvement in a single arm row is very minimal, used only as minorstabilisation (stabilisation in a rowing movement is provided primarily by the rotator cuff, medial and posterior deltoids). In a row, the triceps are not a prime mover, and shouldn't be felt to be working.
Traditionally, a well performed row will involve: Lats, Traps, Biceps, Posterior (and a little medial) deltoid, rhomboids, rotator cuff, and a little spinae erectae. With the prime movers being the Lats, Biceps and Posterior Delts.
If you can feel triceps, summat weird is occuring

The only way you work the tris is to maintain lat, trap bis and delt engagement, and actively pushing against their resistance.
Ant