How works search module in prestashop?

[Masternet]

Hello everyone,

I need help because I can not understand how search module works ...
In search preferences I set the minimum word length (I put 3), I rebuilt the index and I don't know exactly what do the other parameters

I want to search 2 references:

Ref C4092A
Searching C4092A -> CORRECT
Searching C40 -> CORRECT
Searching 92A -> Not found

Ref C7115A
Searching 15A -> Not found
Instead, It listed items that have "1.5A" in the specifications sheet

Anyone know exactly how works the search module?
If anyone is looking for a reference must known the full reference?

Help, please ...