In the agricultural sector, where reliability, efficiency, and cost-effectiveness are paramount, selecting the right motor starting technique is crucial for ensuring smooth operations and maximizing productivity. In this introduction to motor starting techniques guide tailored specifically for the farming community, we delve into four primary motor starting techniques: Variable Speed Drives (VSDs), Star Delta Starters, Direct Online (DOL) starters, and Manual Motor Starters, evaluating their respective pros and cons to help the farming community make informed decisions that suit their unique needs and challenges specifically in their farming niche.

Variable Speed Drives (VSDs):


Energy Efficiency: VSDs offer precise control over motor speed, allowing farmers to match the motor’s output to the specific requirements of their agricultural machinery. Whether it’s adjusting the speed of irrigation pumps or controlling the operation of grain conveyors, VSDs enable farmers to optimize energy usage and reduce electricity costs by operating their equipment at the most efficient speeds.

Soft Start: With VSDs, farmers can avoid sudden jolts and mechanical stress on their equipment during startup. The soft start feature gradually ramps up the motor’s speed, reducing wear and tear on belts, gears, and other components. This gentle starting method extends the lifespan of agricultural machinery, minimizing downtime and repair expenses over the long term.

Customized Control: VSDs provide farmers with the flexibility to tailor motor speed and torque according to specific tasks and conditions. Whether it’s adjusting the flow rate of irrigation systems based on soil moisture levels or optimizing the speed of grain augers for efficient handling, VSDs empower farmers to fine-tune their operations for maximum productivity and resource utilization.


Initial Investment: While VSDs offer significant long-term savings through energy efficiency and equipment protection, the upfront cost of purchasing and installing these systems may pose a challenge for some farmers, particularly those with limited capital or smaller-scale operations. However, it’s essential to consider the return on investment in terms of energy savings and productivity gains over the lifespan of the equipment.

Complexity: Operating and maintaining VSDs require a certain level of technical expertise and familiarity with electronic controls. Farmers may need to invest time and resources in training or consulting with experts to ensure proper installation, programming, and troubleshooting of VSDs. Additionally, the presence of electronic components and sensitive circuitry may make VSDs more vulnerable to damage from environmental factors such as dust, moisture, or power surges.

Star Delta Starters:


Simplicity: Star delta starters offer a straightforward and reliable method of starting induction motors commonly used in farming equipment such as pumps, fans, and compressors. With their simple design and minimal components, star delta starters are easy to install, operate, and maintain, making them well-suited for agricultural applications where robustness and ease of use are essential.

Reduced Starting Current: By initially connecting the motor windings in a star configuration during startup, star delta starters help minimize the inrush current drawn from the power supply (33%). This reduces voltage fluctuations and prevents overload conditions, ensuring stable operation of agricultural machinery without putting undue stress on the electrical infrastructure.

Cost-Effectiveness: Compared to more advanced starting methods like VSDs, star delta starters offer a cost-effective solution for farmers seeking reliable motor control without the complexity or expense of electronic systems. The affordability of star delta starters makes them accessible to farmers of all scales, from small family farms to large commercial operations, looking to optimize their equipment performance within budget constraints.


Limited Speed Control: While effective for starting induction motors, star delta starters provide limited control over motor speed once the motor is running in the delta configuration. Farmers may find themselves constrained by the fixed speed settings of their equipment, limiting their ability to adapt to varying field conditions or operational requirements. For applications requiring precise speed regulation, alternative starting methods such as VSDs may be more suitable.

Mechanical Stress: The transition from star to delta connection during startup can introduce mechanical shock and torque fluctuations, particularly in high-inertia systems such as grain augers or feed mixers. Farmers should carefully assess the impact of these transient forces on their equipment and implement appropriate measures to mitigate mechanical wear and ensure long-term reliability.

Direct Online (DOL) Starters:


Simplicity: DOL starters offer a straightforward and cost-effective solution for starting single-phase or three-phase motors commonly found in agricultural machinery. With their simple push-button or switch-operated design, DOL starters are easy to install and operate, requiring minimal training or technical expertise. This simplicity makes them ideal for farmers seeking reliable motor control without the complexity of electronic systems.

High Starting Torque: By supplying full voltage to the motor from the outset, DOL starters provide maximum starting torque, ensuring rapid acceleration and efficient operation of agricultural equipment such as grain elevators, silo unloaders, or livestock feeding systems. Farmers can rely on DOL starters to deliver the power and performance needed to handle heavy loads and demanding operating conditions.


High Inrush Current: One of the primary drawbacks of DOL starters is the high inrush current drawn from the power supply during startup. The sudden surge of current can lead to voltage drops, flickering lights, and increased stress on the electrical infrastructure, particularly in rural areas with limited grid capacity. Farmers should consider the potential impact of high inrush currents on their electrical system and implement measures such as staggered starting or capacitor banks to mitigate these effects.

Limited Efficiency: While effective for starting motors and providing high torque output, DOL starters offer limited energy efficiency compared to more advanced starting methods like VSDs. The constant-speed operation of DOL starters may result in unnecessary energy consumption and higher operating costs, particularly for equipment running at partial load or operating intermittently. Farmers should weigh the long-term energy savings against the upfront cost of implementing energy-efficient starting solutions.

Manual Motor Starters:


Reliability: Manual motor starters offer a dependable and straightforward method of motor control, relying on mechanical switches or push-button controls for operation. With their simple and robust design, manual starters are well-suited for agricultural applications where reliability is paramount, and electronic or automated systems may be prone to malfunction or environmental damage.

Cost-Effectiveness: Manual motor starters are typically the most cost-effective option for smaller electrical motors used in agricultural equipment such as pumps, fans, or augers. With their simple construction and basic functionality, manual starters offer an affordable solution for farmers looking to control motorized equipment without investing in complex or expensive electronic systems. This cost-effectiveness makes manual starters accessible to farmers of all scales, from small family farms to larger commercial operations.


Limited Automation: One of the primary limitations of manual motor starters is their lack of automation and remote-control capabilities. Unlike electronic or programmable systems, manual starters rely on direct manual input from operators to start, stop, or control motorized equipment. While suitable for simple applications or standalone machinery, manual starters may not be well-suited for control and integrated feedback.


Riken Electric stocks the full range of motor starting equipment and control gear. Our experienced technical solutions team is dedicated to assisting you in choosing the most suitable starter for your application, ensuring optimal performance and efficiency. For personalized guidance and expert advice, please contact our offices at 012 804 2226 and ask for Jaco. We’re here to help you find the perfect motor start and control solution for your requirements.