At least two types of 3-phase electric motor starter are available: Direct-On-Line (DOL) and Star-Delta.
For more information about how they work, and the differences between them, see the answers to the Related Questions shown below.
DOL starter involves direct switching of polyphase squirrel cage induction motor to supply mains . Star delta starter is based on the principle that 3 windings connected in star, the voltage across each winding is 57.7% of line to line voltage whereas the same winding in delta will have full line to line voltage across each
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With DOL, the full line supply voltage is applied to the motor windings at starting. This is commonly used where the motor is not starting under load or under a heavy load.
Star-Delta,In this case a reduced voltage is applied to the windings at starting and it's achieved since the phase voltage is a quotient Line voltage divided by 1.703. After the motor has attained speed, usually 3 seconds, the full line supply voltage is then applied to the motor windings.
The DOL is nowadays the most common type of 3-phase motor starter used.
A Direct-On-Line (DOL) starter is an electronic 3-phase motor-control system which offers soft starts in DELTA configuration.
In the DOL way of starting a 3-phase motor, full line voltages are applied to the motor through relays and contactors.
It has a "closing circuit" and an "opening circuit". The closing circuit is for applying the service lines to the motor and the opening - or "tripping" - circuit protects the motor by cutting-off (or "tripping") power to the motor from the service lines if there is any overload condition, a single phasing fault, etc.
For more information please see the answers to the Related Question shown below.
A star delta starter brings the motor up to operating speed in two steps. A soft start brings the motor up to speed in multiple steps that can be programmed into the starter. Soft start starters have the option of having a bypass contactor in the circuit so that when the motor comes up to operating speed the bypass contactor pulls in and the soft start is dropped out of the circuit.
Direct on line starter and Heavy direct on line starter...... in HDOL CT is fixed.
There is a link below for the DOL starter circuit.
for smooth operation and also to reduse starting current
Yes up to certain rating and application a motor can be started on DOL. Beyond a rating different methods need to be used to limit the starting current.
A Direct-On-Line (DOL) starter is an electronic 3-phase motor-control system which offers soft starts in DELTA configuration. DOL starters are now replacing the use of manual or semi-automatic "star-delta" starters.In this way of starting a 3-phase motor, full line voltages are applied to the motor through relays and contactors. The DOL is nowadays the most common type of 3-phase motor starter used.It has a "closing circuit" and an "opening circuit". The closing circuit is for applying the service lines to the motor and the opening - or "tripping" - circuit protects the motor by cutting-off (or "tripping") power to the motor from the service lines if there is any overload condition, a single phasing fault, etc.For more information please see the answers to the Related Questions shown below.
Direct on line starter and Heavy direct on line starter...... in HDOL CT is fixed.
A DOL or direct on line starter works by connecting the motor terminals directly to the power supply when they are energized. A DOL starter is the simplest type of motor starter.
The answer is yes. I had seen 110kW pump start on DOL starter
DOL starters are used in industries in-spite of its disadvantages because it is the simplest form of a motor starter. A DOL starter consists of a MCCB or circuit breaker, contactor, and an overload relay that is used for protection.
DOL, Star Delta, Soft starter, VFD
with the help of senser
There is a link below for the DOL starter circuit.
function of dol stater
DOL or Direct On Line is used when referring to induction motor starters. The simplest and most common type of motor starter is the Direct On Line. Some examples where a DOL starter would be used can include water pumps, compressors, conveyor belts and fans. A DOL starter can only be used if the sudden inrush of the motor starting does not cause voltage to drop excessively in the supply circuit.
for smooth operation and also to reduse starting current
DOL, Star Delta, Soft starter, VFD
If the application is high starting torque, then go for star delta or soft starters. If not DOL will do.