We numerically assess how chordwise placement of a single dielectric barrier discharge (DBD) plasma actuator affects separation control on a cambered NACA 6412 airfoil at α = 12° for U∞ = 1 and 10 m/s (Re ≈ 6.85×10^4 and 6.85×10^5, respectively). Steady RANS (SST k-ω) is coupled with a Shyy-type body-force model to represent the actuator. In the baseline, separation forms on the suction side with onset near x/c ≈ 0.60 at 1 m/s and x/c ≈ 0.70 at 10 m/s. Four plasma actuator locations are evaluated: x/c = 0.03 (LEL), 0.10 (LER), 0.40 (TEL), and 0.65 (TER). Simulation results indicated that placement strongly governs authority by determining where momentum is added to the boundary layer. A leading-edge actuator at x/c ≈ 0.03 consistently yields the best outcome, delaying or removing separation, strengthening the suction peak, and promoting smooth pressure recovery, especially at 10 m/s. A downstream actuator near x/c ≈ 0.65 is the next most effective, targeting the vicinity of natural separation. LER (x/c ≈ 0.10) is the least effective, especially at 10 m/s, where residual trailing-edge separation remains. For placements aft of the maximum thickness, very strong actuation (plasma jet ≫ free-stream) can induce a laminar separation bubble and increase drag despite lift gains. These findings offer practical guidance for selecting actuator position and strength on cambered airfoils at moderate incidence.