Time on 24 hour clock

Question

Could you provide additional explanation for this: When the time expressed uses hour numbers above 12 (in the "24-hour clock" -> 13h, 14h...), you use instead quinze, trente, quarante-cinq, probably for pronunciation (and elegance) . 
 
I am having a hard time understanding these translations in the examples of a 24 hour clock. 
Il est seize heures quinze.It is quarter past four PM.​​Il est quinze heures trente.It is three-thirty PM.Il est dix-neuf heures quarante-cinq.It's quarter to eight PM.

Accepted Answer

seize heure quinze -- 16:15 -- 4:15 pmquinze heures trente -- 15:30 -- 3:30 pmdix-neuf heures quarante-cinq -- 19:45 -- 7:45 pm
As you can see, in the 24-h clock you just express hours and minutes as the numbers they are. Ease of pronunciation doesn't come in.