Large Transport; Low Wing; 2 Turbojet Eng
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 6
Confusion; Distraction; Other / Unknown; Situational Awareness
ATC Issue All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Separated Traffic
Airspace Structure; Human Factors; Procedure
While working R1-R5 positions combined; Aircraft X departs SJU on a 350 heading climbing to 5;000 ft.  As soon as he leaves the SJU tower airspace I cleared him direct JAAWS to join the JAAWS9 departure. X miles behind the tower sends Aircraft Y on the same heading; climbing to 5;000ft.  As soon as I have communication with Aircraft Y; I stop him at 3;000ft because he climbs much faster than the Aircraft X.When I stopped him; Aircraft X was still climbing out of 4;000 ft.  Within the minute; Aircraft Y was less than 3 miles behind Aircraft X.  Because I stopped his climb; they maintained radar separation.  A few months back our LOA with SJU tower provided us with 5 miles in trail separation for same headings departures.  Even though 3 miles is radar separation approved by the 7110.65; our airspace configuration is a little complicated; there is a lot of crossing traffic even for departures; and we have to provide the center 5 miles in trail separation.  We have numerous times asked management to change the LOA back as it was before; but our request have been ignored multiple times.We obviously have a safety issue here.  Whether is the LOA or training CPCs at the SJU tower.  But this situation has happened more than once in less than a week.  Clearly something needs to be done.  Had I been busy; distracted; frequency failure; they would have lost separation.  Either we change the LOA or train CPC's better with aircraft characteristics and radar separation.  It took me a few days to complete this report; my password was reset but took a few days to receive email.
ZSU Controller reports of saving a loss of separation by using altitude. Tower Controller did not provide enough spacing to allow faster climbing departure following slower climbing departure.