ELECTRICALE4U

Construction of DOL Starter It consists of two buttons, GREEN for starting and RED for stopping purpose of the motor. The DOL starter comprises of an MCCB or circuit breaker, contactor and an overload relay for protection. These two buttons, i.e. Green and Red or start and stop buttons control the contacts. To start the motor, we close the contact by pushing Green Button, and the full line voltage appears to the motor. Contactor can be of 3 poles or 4-pole. Below given contactor is of 4-pole type. It contains three NO (normally open) contacts that connect the motor to supply lines, and the fourth contact is "hold on contact" (auxiliary contact) which energises the contactor coil after the start button is released. If any fault occurs, the auxiliary coil gets de-energised, and hence the starter disconnects the motor from supply mains. Overload Protection When motor draws excessive current to meet the load requirement and If load requirement goes beyond the ra