We all have been accustomed to the warm, orange-golden lighting of our cities. This is not surprising, because the HPS lamps in most cases illuminate our streets and are one of the most effective sources of light. The first to massively begin to use were low-pressure lamps - LPL, which were replaced by more technological mercury gas-discharge lamps, and those in turn were replaced by HPSL- high-pressure sodium-vapor lamps. What is a sodium-vapor lamp? HPS (high pressure sodium ...