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

HP Rating DOL Range
Starters Controller
MK1 MF1 MU1 MB1 MU2 MB2 ML1.5 ML2 MU-G6 MU-G10 MU-G10H
0.25 - 2
3 - 6

DOL Starters:

  • MK1 DOL - with MK1 contactor and MK1 relay
  • MU DOL - with MU contactor and MU relay
  • MB DOL - with MU contactor and MN relay
  • ML DOL - with MU contactor and MN relay


  • MU-G6 – with MK1 contactor, MK1 relay and Sz5 (SPPR)
  • MU-G10 & MU-G10H - with MU contactor, MU relay and Sz5 (SPPR)