PSA data packets broken up into several smaller packets

Hi All,

I am facing an issue while loading data from R3 to BW 3.5.

I am loading data till PSA and the Infopackage data packet size is maintained as 20000.

In the Infopackage Monitor Details tab,the Extraction step says every data packet contains around 16K records.

But when it is loading to the PSA in the Processing step,each data packet breaks up into several small data packets of size 1500 records.

There are no transfer rules.

Could anyone tell me the reason for this sporadic burst and solution to have a larger data packet loaded into PSA in spite of maintaining it in the Infopackage settings?

Thanks!!!