Direct On Line (DOL) starter is the most fundamental, economical, as well as a simplest method for running a three-phase induction motor. In here, I have explained three phase DOL starter with indicator lights for induction motor. The Direct On Line Motor Starter (DOL) consists of an MCB, Magnetic Contactor and a thermal overload relay for protection.
The applications of DOL starters are primarily motors where a high inrush current does not cause excessive voltage drop in the supply circuit (or where this high voltage drop is acceptable).
Different starting methods are used to start 3 phase induction motor like star delta starter, autotransformer starter, variable frequency drive, soft starter, dol starter (direct online starter) because the induction motor draws a large current at starting.
Direct On-Line is the simplest and cheapest method used for starting a three-phase motor. Doll is used for up to 5 HP motor. Doll starter is more popular due to its low price.
DOL starter connects the motor directly to the supply without a reduction in supply voltage and applies full line voltage to 3 phase motor. This is the main disadvantage of doll starter.
A small HP motor can be started simply by plugging into the power supply. But large HP motor required a special unit called a motor starter.
Direct online starter for 3-phase induction motor contain parts like miniature circuit breaker (MCB) for motor protection purpose, overload relay, power contactor, fuse unit, start button, stop button.
Small size dol starter is operated manually but for larger HP motor, dol motor starter are operated using electromechanical contactor (relay) to switch motor ON and OFF.
DOL Motor Starter can be used if a high starting current cannot cause an excessive voltage drop in the motor circuit.
The demerits of doll starter is that gives the highest possible current to motor. Which is 6 to 7 time of rated current of the motor.
Besides the DOL starter draws the starting current there also exists a current peak that can rise up to 14 times the rated current since the motor is not energized from the first moment when starting.
DOL starter control circuit diagram consists of components like Main power contactor, start button, stop push button and overload relay is connected in series. This circuit is called control circuit of dol motor starter. All controlling of starter are controlled by this circuit.
DOL starter power circuit diagram:
Direct Online starter power diagram has fuse unit, Main power contactor (K1), overload relay. Also, we can connect the MCB for protection purpose in a direct On-Line motor starter.
Direct On Line (DOL) starter is the most fundamental, economical, as well as a simplest method for running a three-phase induction motor. In here, I have explained three phase DOL starter with indicator lights for induction motor. The Direct On Line Motor Starter (DOL) consists of an MCB, Magnetic Contactor and a thermal overload relay for protection.
The applications of DOL starters are primarily motors where a high inrush current does not cause excessive voltage drop in the supply circuit (or where this high voltage drop is acceptable).
Different starting methods are used to start 3 phase induction motor like star delta starter, autotransformer starter, variable frequency drive, soft starter, dol starter (direct online starter) because the induction motor draws a large current at starting.
Direct On-Line is the simplest and cheapest method used for starting a three-phase motor. Doll is used for up to 5 HP motor. Doll starter is more popular due to its low price.
DOL starter connects the motor directly to the supply without a reduction in supply voltage and applies full line voltage to 3 phase motor. This is the main disadvantage of doll starter.
A small HP motor can be started simply by plugging into the power supply. But large HP motor required a special unit called a motor starter.
Direct online starter for 3-phase induction motor contain parts like miniature circuit breaker (MCB) for motor protection purpose, overload relay, power contactor, fuse unit, start button, stop button.
Small size dol starter is operated manually but for larger HP motor, dol motor starter are operated using electromechanical contactor (relay) to switch motor ON and OFF.
DOL Motor Starter can be used if a high starting current cannot cause an excessive voltage drop in the motor circuit.
The demerits of doll starter is that gives the highest possible current to motor. Which is 6 to 7 time of rated current of the motor.
Besides the DOL starter draws the starting current there also exists a current peak that can rise up to 14 times the rated current since the motor is not energized from the first moment when starting.
DOL starter control circuit diagram consists of components like Main power contactor, start button, stop push button and overload relay is connected in series. This circuit is called control circuit of dol motor starter. All controlling of starter are controlled by this circuit.
DOL starter power circuit diagram:
Direct Online starter power diagram has fuse unit, Main power contactor (K1), overload relay. Also, we can connect the MCB for protection purpose in a direct On-Line motor starter.
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