Direct Online Starter; MK_1 by L&T
DOL stands for DIRECT ONLINE In this starter, Motor get directly connected to power supply without any change in voltage, frequency & winding connections, That's why starter name is Direct On Line.
MK-1 DOL Starters are most widely used starter in Industry for small rating induction motors. Best part of this MK-1 starter is; Its Every smallest single part is easily replaceable.
Like any other DOL starter, It also consists of thermal overload relay, Contactor & push button unit. We are going to discuss all these parts one by one.
1. Thermal Overload Relay
Thermal overload relay is a protection device which protect the motor in overload conditions.
Motor's rated current depend upon the power rating of the motor that's why this thermal overload relay comes in different ampere ranges; Like 1.5-2.5Amps, 2.5-4Amps, 4-6.5Amps, 6-10Amps, 9-14Amps.
Contactor in this starter; is a part which connects output terminals of overload relay with motor terminals. This contactor consists of plunger, Electromagnetic coil & motor terminals.
A pair of push button are fitted on the cover of the starter; Just in front of the thermal overload relay. The pair of push button in which STOP button pushes the NC & START button pushes NO contact of thermal overload relay.
Hope, This post has something helpful. For any query or suggestion you are always welcome. Please do comments !