The 900 ks Chandra spectrum of NGC 3783 was analyzed in various ways to study the properties of the absorbing gas. The main findings are: 1) On a time scale of 20-120 days, the source exhibits two very different spectral shapes with different softness ratios. The absorbing gas is not responding to these continuum variations. 2) Detailed photoionization modeling based on 10 silicon and sulphur lines near 5-7Å produces a satisfactory fit of the entire 3-25 A spectrum of the source. The only discrepancy is in the central wavelength of the iron UTA feature. 3) A combination of three ionized absorbers, each split into two kinematic components, can explain the strengths of almost all the absorption lines and bound-free edges. The three components span a large range of ionization and have a total column of about 4×1022 cm-2. Moreover, all three components are thermally stable and seem to have the same gas pressure.