Direct On-Line (DOL)
Direct On-Line (DOL) method is the simplest starting method for 3-phase pump set. L&T offers two variants of DOL method – starter and controller.
DOL starters are basic electrical starters with contactors and relay for ON/OFF operation and overload protection of the pump set. Over and above the ON/OFF operation and overload protection features equipped in Controllers, it also provides additional features like Auto ON, indications of Supply ON/OFF and Pump ON/OFF, reading of real time voltage & current of pump with unique Dual analog meter. Single phasing protection relay (SPPR) inside Controller unit provides the advanced protection features viz. single-phasing prevention, phase-reversal protection, phase-unbalance protection, variable time-delay adjustment for delayed operation of pump set