DOL STARTER CONTROL DIAGRAM
In case of small rating motors having less than 05HP motors. The starting current is not so very high and these motors can withstand starting current without any starters. Thus there is no need to reduce the applied voltage to control the starting current. Such motors use a type of starters which connects the stator winding directly to the supply without reduction in voltage. therefore the starter is known as DOL (DIRECT-ON-LINE)starters. This starter does not reduce applied voltage but protects from various ways like overloading, under voltage, single phasing etc.
- Magnetic contactors
- Over load relay protection
- No(normally open)
- Nc(normally closed)
Magnetic contactors:- magnetic contactors is an electrically controlled switch used for switching a power circuit similar to relay except with higher current rating. A contactor is controlled by a circuit which has much lower level than the switched circuit.Magnetic contactors consist of a coil which produces magnetic field.the contactors are consist of additional contacts i.e-NO(Normally Open) and NC(Normally Closed).
No(normally open):-when start button is pushed the motor is on till the button is pressed therefore NO contact is used in the contactors.NO contact ensures that the motor remains in on condition when button is left.
NC(Normally Closed):- when stop button is pressed NC contact in the contactor is breaks the circuit and motor will stop.
Over Load Relay:- over load relay protection is used for the protection of motor against over current, over voltage and under voltage. It comes with the selection of amperes.
when we press the start button to start the motor the relay gets the phase and circuit completed thus coil energizes and contactors produce magnetic field .the main contactor closes and motor gets the supply and the motor starts.When we press the stop button the circuit will interrupt and the motor stop.
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