  We present a detailed spectral analysis of the data obtained from NGC 3783
during the period 2000-2001 using Chandra. This analysis leads us to the
following results. 1) NGC 3783 fluctuated in luminosity by a factor ~1.5 during
individual observations (~170 ks duration). These fluctuations were not
associated with significant spectral variations. 2) On a longer time scale
(20-120 days), we found the source to exhibit two very different spectral
shapes. The main difference between these can be well-described by the
appearance and disappearance of a spectral component that dominates the
underlying continuum at the longest wavelengths. The spectral variations are
not related to the brightening or the fading of the continuum at short
wavelengths in any simple way. 3) The appearance of the soft continuum
component is consistent with being the only spectral variation, and there is no
need to invoke changes in the opacity of the absorbers. 4) Photoionization
modeling indicates that 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. All three components are thermally
stable and seem to have the same gas pressure. 5) The only real discrepancy
between our model and the observations concerns the range of wavelengths
absorbed by the iron M-shell UTA feature. This most likely arises as the result
of our underestimation of the poorly-known dielectronic recombination rates
appropriate for these ions. 6) The lower limit on the distance of the absorbing
gas in NGC 3783 is between 0.2 and 3.2 pc. The assumption of pressure
equilibrium imposes an upper limit of about 25 pc on the distance of the
least-ionized component from the central source. (abridged)
