Direct Online Starter

March 24, 2024 Post a Comment

Direct online starter

In the DOL method of starting a squirrel cage induction motor, the motor is connected to the full supply voltage through a starter. The direct-on line starter consists of a coil operated contactor C which is controlled by start (normally open) push button and stop (normally closed) push button.

What are the types of DOL starter?

There are 5 types of starters are used to start electrical such as

DOL – Direct online starter – Motor range below 10 HP. Stator resistance starter-
Star- Delta starter – above 10 HP Motor.
Autotransformer starter – above 1 HP.
Soft starter – motor range above 150 HP.
VFD – Any range of motor.

What does DOL mean in electrical?

Direct on line (DOL) motor starting is when a motor is started at full load, with full line voltage applied to motor terminals. As this causes the motor to draw a large amount of current, it is only suitable for motor powers up to 4Kw, with a maximum motor size of 10Kw connected this way.

What is difference between DOL and Star Delta?

As you will see, the DOL starting method features a very high locked-rotor current which eventually flattens and becomes constant. The star-delta starting method features a lower locked-rotor current, but peaks during the starting process as the changeover from star to delta is made.

How much horsepower does a DOL starter use?

Dol is used for up to 5 HP motor. dol starter is more popular due to the low price. DOL starter connects the motor directly to supply without a reduction in supply voltage and applies full line voltage to 3 phase motor.

Why DOL starter is used up to 5 HP?

Detailed Solution. The direct on line (DOL) starter method of an induction motor is simple and economical. In this method, the starter is connected directly to supply voltage. By this method, small motors up to 5 kW rating are started to avoid the supply voltage fluctuation.

What are the 4 types of starters?

Types of Magnetic Motor Starters

Direct-On-Line Starter. The direct-on-line starter is the simplest form of motor starter, other than a manual starter.
Rotor Resistance Starter. ...
Stator Resistance Starter. ...
Auto Transformer Starter. ...
Star Delta Starter.

What is the range of DOL starter?

D.O.L Starters: Range: 0.5 to 7.5Hp: Contactor protects the motor against under voltage where as the relay protects the same against overloads.

Why do we need DOL starter?

The DOL starters are used for motor having low power ratings. Where the starting current does not damage the windings of the motor. For applications where the starting current does not cause huge dips in the line voltage. Direct online starters are used for small water pumps, conveyor belts, fans and compressors.

What is direct online starter used for?

DOL Starter Applications Direct on line starters are commonly used to start small water pumps, conveyor belts, fans, and compressors. In the case of an asynchronous motor (such as the 3-phase squirrel-cage motor) the motor will draw a high starting current until it has run up to full speed.

Can we use DOL starter for 10 hp motor?

You can purchase SJ 13-21A 10 H.P For Motor 3 Phase DOL Starter - S02/A of the finest quality and rest assured to get the best in terms of both durability and performance.

How do I choose a DOL starter?

As per above chart:

Type of Contactor = AC7b.
Size of Main Contactor = 100%X Full Load Current (Line).
Size of Main Contactor = 100%x6 = 6 Amp.
Making/Breaking Capacity of Contactor = Value above Chart x Full Load Current (Line).
Making/Breaking Capacity of Contactor = 8×6 = 52 Amp.

Which relay is used in DOL starter?

The Direct On Line Motor Starter (DOL) consist a MCCB or Circuit Breaker, Contactor and an overload relay for protection. Electromagnetic contactor which can be opened by the thermal overload relay under fault conditions.

Why we use DOL or star-delta starter?

DOL starter is suitable and cheapest method to start up motor only for normaler sizes motor, for larger motor must use the star-delta starter.

What is the difference between star-delta and direct online starter?

Star delta starter takes the run up time of approximately 2 to 15 seconds. On the other hand the DOL starter takes the starting time of approximately 2 to 5 seconds. These starting times are also affected by the amount of the load.

Can we use DOL starter for 15 HP motor?

It is designed for use with submersible pumps and motors and is rated for up to 15 HP. This starter is easy to install and comes with a best-in-market price.

Which starter is used for 7.5 HP motor?

The Oil Immersed Motor Starter has a motor rating of AC3 and a voltage of 415V. It has three phases and its frequency rate is 50 Hz. The power HP of the Oil Immersed Motor Starter is 7.5 HP and has a motor rating of AC 3.

Which of the starter is used for highest HP?

The Star Delta Starter is used to limit the starting current of the induction motor. These starters are available up to 180 Hp and can be used in the industries like- Textile, Food & Beverages, Sugar Plants, Paper & Printing, Cold Storages, etc.

What is reverse DOL starter?

Reverse DOL Starter (RDOL) An RDOL reversing starter can connect to the motor for rotation in either direction. Such a starter contains two DOL circuits – one for clockwise operation and the other for counter-clockwise operation, with mechanical and electrical interlocks to avoid closure at the same time.