Extract from Evolution of Indian launch vehicle technologies published in CURRENT SCIENCE, VOL. 93, NO. 12, 25 DECEMBER 2007PSLV was designed in 1980s for inserting 1 ton class of operational remote sensing satellites into Sun synchronous orbit. It was truly a quantum leap for Indian space technology at that time as a follow-on project of the ASLV. PSLV today is among the few launchers with a very high success rates and serves as the work-horse of ISRO.
Different configurations are designed to provide wide variations in payload capabilities ranging from 600 kg in LEO to 1900 kg in SSPO. Core-alone configuration without strap-on motors is designed to launch two satellites of 400 kg each into LEO. A three-stage configuration without strap-on motors and liquid stage will offer lower launch cost of 500 kg class of satellites into LEO.
The most interesting of these variants are the PSLV-HP and PSLV-3S, the most capable and least capable members of the PSLV family if built. The PSLV-HP is supposed to have a a capability of 1900 kg to SSPO. It was designed to launch the IRNSS constellation into orbit but there are doubts over the program following the revelation by ISRO that it was looking into the possibility of GSLV launching the IRNSS. The 3S variant without the PSLV second stage is designed to launch 500 kg payload into a 550 km LEO.