DOL / Star-Delta Starter Panel

Direct-On-Line and Star-Delta motor starters — simple full-voltage or reduced-current starting.

DOL (Direct-On-Line) and Star-Delta are motor starter panel types: DOL offers simple, full-voltage starting for small motors (high current/torque), while Star-Delta uses a two-step process (Star for reduced current/torque, then Delta for full power) for larger motors to limit inrush current, reducing stress but adding complexity and cost. DOL Starter Panel: connects the motor directly to full supply voltage using a main contactor, overload relay and stop/start buttons — simple and cheap, with high starting torque (100%), but high starting current (6–8x full-load current); best for small motors (<5HP/7.5kW) needing high initial torque. Star-Delta (Δ-Y) Starter Panel: starts in Star for reduced voltage (58%) and current (1/3), then switches to Delta for full operation, using three contactors, a timer and an overload relay — reduced starting current (2–3x FL current), smoother start, less mechanical stress; best for medium to large motors (>5HP/7.5kW) where current draw must be limited. Both types offer overload and phase-loss protection, with auto/manual modes and remote control options.