Tuesday, 13 August 2013

Principle of DOL starter:

A Direct-On-Line (DOL) starter is an electronic 3-phase  control framework which offers delicate begins in DELTA conneection. DOL starters are presently replacing the utilization of manual or semi automatic "star-delta" starters. In the  beginning of a 3-Phase Induction motor, full line voltages are connected to the motor through contactors. The DOL is these days the most widely recognized sort of 3-Phase starter utilized.

It has an "closing circuit" and an "opening circuit". The closing circuit is for applying the supply lines to the motor and the opening -or "tripping" -circuit secures the motor by cutting-off (or "tripping") power to the motor from the administration lines if there is any over-load condition, single phasing fault etc.

DOL starting is sometimes used to start small  water pumps, compressor , fans and Conveyor belts. In the case of an asynchronous motor, such as the 3-phase, the motor will draw a high starting current until it has run up to full speed. This starting current is typically 6-7 times greater than the full load current. To reduce the inrush current, larger motors will have reduced-voltage starters or variablespeed drives in order to minimise voltage dips to the power supply.


 DOL starters are now and then used to start minor water pumps, compressor , fans and Conveyor cinchs For  induction motors, for example the 3-phase induction motor will draw a high beginning current until it has run up to full speed. This beginning current is regularly 6-7 times more stupendous than the full load current. To lessen the inrush current, bigger motors will have decreased voltage starters or variablespeed drives so as to minimise voltage dips to the force supply.

Connection Diagram of D.O.L starter:







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