DOL Starters for Agricultural Motors and Pump Sets

DOL starters, also known as Direct-On-Line starters, are a type of electromechanical device used to start and stop electric motors. These starters are straightforward and commonly used for small to medium-sized motors in various industrial applications. The main components of a DOL starter include a contactor, an overload relay, and a start button.

3-phase DOL starters are commonly used for motors with relatively small to moderate power ratings, where the instantaneous application of full voltage does not cause excessive stress on the motor or the connected load. However, for larger motors or applications where a softer start is needed to reduce mechanical and electrical stress, other starting methods like star-delta starters or variable frequency drives (VFDs) may be preferred.

How does a 3-phase DOL starter work?

The sequence of operation in a 3-phase DOL starter is as follows:

• The motor is at rest, and the start button is pressed.
• The contactor coil is energised, closing the contacts and connecting the motor to the power supply.
• The motor receives the full voltage, and it starts running.
• The overload relay continuously monitors the motor current during operation.
• If the current exceeds the pre-set level (indicating an overload or fault), the overload relay opens the circuit, de-energizing the contactor and stopping the motor.

Are DOL starters suited for agricultural motors and pump sets?

Yes, Direct-On-Line (DOL) starters are commonly used for agricultural motors and pump sets. These starters are well-suited for applications where the motor load is relatively constant and there is no requirement for a soft or gradual start. Agricultural motors, especially those driving pump sets for irrigation or other purposes, often fall into this category.

The advantages of using DOL starters in agricultural applications include their simplicity, cost-effectiveness, and reliability. Since many agricultural processes involve turning on the motor to operate equipment such as pumps, fans, or conveyors, and then turning it off when the operation is complete, the on/off nature of DOL starters aligns well with these requirements.

However, it's important to consider a few factors:

Motor Rated Current:

Make sure to check the motor rated current and select suitable relay range for choosing your starter.

Overload Protection:

Ensure that the DOL starter includes an overload relay to protect the motor from excessive current and overheating. This is crucial for preventing damage to the motor during prolonged use or in the event of a fault.

Alternative to DOL:

Depending on the specific requirements and conditions of the application, you may also consider other types of starters such as star-delta starters or variable frequency drives (VFDs), which provide softer starting methods and additional control features. These alternatives are often used when it's necessary to reduce starting current or provide variable speed control.

Top features of Lauritz Knudsen (Formerly L&T Switchgear) DOL starters

Lauritz Knudsen (Formerly L&T Switchgear) is an established name in the electrical equipment manufacturing industry. We manufacture high-quality DOL motor starters with,

• Wide operating voltage range
• 200-400 volt wide band coil operation
• Reliable protection against overload
• Reliable operation under adverse field conditions including hot and humid conditions, supply voltage imbalance etc.
• Visible “ON & OFF” indication
• Rugged silver tipped contacts for long lasting usage
• Durable enclosure for protection against dust, humidity and insects
• Compatibility with Voltage/Current Auto Single Phase Preventer (SPPR)
• Functionality to connect with Dry Run Protection device

What is the operating range of Lauritz Knudsen (Formerly L&T Switchgear) DOL starters?

To obtain accurate and current information about Lauritz Knudsen (Formerly L&T Switchgear) DOL starters, we recommend checking the following sources:

• Lauritz Knudsen (Formerly L&T Switchgear) Official Website:

  The official website of Lauritz Knudsen (Formerly L&T Switchgear)  is a primary source for product information. Manufacturers typically provide detailed specifications, datasheets, and documentation for products on the official websites.

• Product Catalogues and Brochures:

  Look for product catalogues, brochures, or technical documents provided by Lauritz Knudsen (Formerly L&T Switchgear). These documents often contain comprehensive information about the specifications, features, and operating ranges of Lauritz Knudsen (Formerly L&T Switchgear) DOL starters.

• Contact Lauritz Knudsen (Formerly L&T Switchgear) Customer Support:

  If you have specific questions or need assistance in choosing the right product for your application, consider reaching out to Lauritz Knudsen (Formerly L&T Switchgear) customer support or sales representatives. They can provide accurate and tailored information based on your requirements.

• Authorised Distributors:

  Authorised distributors or dealers of Lauritz Knudsen (Formerly L&T Switchgear) products may also have information on the operating ranges of DOL starters. They can assist you in obtaining the relevant documentation or direct you to the appropriate resources.

Remember that product specifications and models may be updated or changed over time, so it's important to refer to the most recent and accurate information from the manufacturer.