Operate Efficiently and Safely with Motor Starters

What are Motor Starters?

Motor starters are electrical devices designed to control the operation of an electric motor. They regulate the electrical power supplied to the motor, enabling it to start, stop, or run under various conditions. A motor starter essentially acts as a switch that turns on or off the power supply to the motor.

However, it does more than merely switch power. It also provides features like overload protection and phase failure protection which prevent damage to the motor and enhance the safety of the overall system. In essence, a motor starter is a device that safeguards the motor and helps optimize its performance.

The use of motor starters is particularly prevalent in industrial settings, where they contribute significantly to the efficiency and reliability of various processes and operations.

The Function of Motor Starters in Industrial Applications

In industrial settings, the role of motor starters is paramount. Electric motors form the backbone of many industrial processes, powering machinery and equipment crucial to operations. However, the sudden influx of electrical power during motor start-up can cause significant mechanical stress, leading to premature wear and tear. Motor starters mitigate this problem by providing a controlled ramp-up of power. This smooth, gradual power increase helps prolong the motor’s lifespan and ensure reliable operation.

Moreover, motor starters offer protective functions. They can detect and respond to potentially damaging conditions such as overloads, short circuits, or phase losses. By cutting off power under these circumstances, motor starters prevent motor damage and reduce the risk of electrical accidents, enhancing safety on the factory floor.

Finally, motor starters contribute to energy efficiency. By regulating motor operations and avoiding unnecessary power consumption during periods of light load, motor starters can help industries reduce their energy usage and operational costs.

Understanding How Motor Starters Work

Motor starters operate based on a fairly straightforward mechanism. At their core, they consist of two main components: contactors and overload relays. The contactor is essentially an electrically-controlled switch that turns the motor on or off. It is designed to handle the high current that motors often draw during operation.

On the other hand, the overload relay is a protective device. It monitors the current flowing to the motor and breaks the circuit if it detects an overload condition — a situation where the motor draws more current than it’s rated for. This is crucial in preventing motor damage due to overheating.

The motor starter works by first allowing the motor to draw the necessary current to start up. Once the motor has reached its operating speed, the starter continues to supply the required running current. If an overload condition occurs, the overload relay will trip, breaking the circuit and stopping the motor to prevent damage. So, in essence, the motor starter acts as the ‘middleman’ between the power source and the motor, regulating and monitoring the electrical flow.

types of motor starters

Different Types of Motor Starters

There are several types of motor starters, each with unique characteristics and suited to specific applications.

  1. Direct-On-Line (DOL) Starters: This is the simplest and most common type. The DOL starter connects the motor directly to the power supply, providing the maximum possible voltage and current at start-up. It’s suitable for small motors that don’t require a high starting torque.
  2. Star-Delta Starters: These starters are used for larger motors. They start the motor in ‘star’ configuration, which reduces the voltage and current during start-up. Once the motor reaches a certain speed, it switches to ‘delta’ configuration for normal operation.
  3. Soft Starters: Soft starters electronically control the voltage supplied to the motor to provide a smooth ramp-up of speed. They’re beneficial for applications where a gradual start and stop are necessary to avoid mechanical stress.
  4. Manual Motor Starters: These starters offer manual control over the starting and stopping of motors. They also provide overload protection.

Each of these motor starters has its advantages and is suited for specific motor control scenarios. The selection of the appropriate motor starter depends on various factors, including the characteristics of the motor and the operational requirements.

How Motor Starters Contribute to Safety

Motor starters play a critical role in promoting safety on the factory floor. They serve as the first line of defense against potential electrical hazards by providing crucial protection mechanisms.

One of the primary safety roles of a motor starter is to provide overload protection. Electric motors can draw excessive current under certain conditions, leading to overheating and potential damage. Motor starters can detect such overload conditions and cut off power to the motor, preventing overheating and potential fire hazards.

Motor starters also protect against phase loss, a condition where one of the three phases in a three-phase system is lost. This can cause the motor to draw more current from the remaining phases, resulting in overheating and potential motor failure. Motor starters can detect phase loss and disconnect the motor, preventing damage.

Also, by controlling the start-up of motors, motor starters prevent sudden jerks that can lead to mechanical stress and potential system damage. They also protect the motor during stoppages, ensuring that the power is cut off appropriately to prevent electrical accidents.

Overall, motor starters contribute significantly to maintaining a safe and reliable working environment in industrial settings.

Advantages of Motor Starters

The implementation of motor starters in industrial settings comes with a host of benefits.

  1. Enhanced Motor Lifespan: By providing a smooth start and stop, motor starters reduce the mechanical stress on motors during operation, thereby prolonging their lifespan.
  2. Overload Protection: Motor starters protect motors from damage caused by overload conditions. This ensures the continuous operation of industrial processes and minimizes downtime due to motor failure.
  3. Improved Energy Efficiency: By ensuring that motors only draw the necessary current, motor starters can contribute to significant energy savings, reducing operational costs.
  4. Safety: By providing protective features like overload, short-circuit, and phase loss protection, motor starters enhance the safety of the electrical system, preventing potential electrical accidents.
  5. Control: Motor starters offer precise control over the motor operations, allowing for adjustments based on the specific needs of the process or application.

The use of motor starters in industrial settings is not just a safety requirement but also a strategic decision that optimizes operations, extends the life of equipment, and reduces operational costs.

Right Motor Starter Selection for Optimized Benefits

Choosing the correct motor starter is pivotal in fully utilizing its benefits. This choice depends on several factors, including motor specifications, application requirements, and environmental conditions.


The motor’s size, type, and starting torque requirements should be considered. For instance, smaller motors that don’t require high starting torque might benefit from a Direct-On-Line (DOL) starter. In contrast, larger motors that need to reduce initial inrush current might be better suited to a star-delta or soft starter.

Application Requirements

The application’s requirements are also essential. If the application demands a smooth start and stop to prevent mechanical stress, a soft starter might be the best fit. On the other hand, if the application requires manual control, a manual motor starter may be preferable.

Environmental Conditions

Lastly, environmental conditions, such as temperature, humidity, and the presence of dust or corrosive materials, can influence the choice of motor starter, as different starters have varying degrees of environmental resistance.

By carefully considering these factors, you can select the most suitable motor starter, ensuring optimal motor performance, increased energy efficiency, and enhanced safety.

Bench Testing: An Essential Step Before Installation

The primary goal of bench testing is to verify that the component is functioning correctly before it is installed and integrated into the larger system.

During a bench test, the motor starter is connected to a power source and a test load, simulating the conditions it will experience during its actual operation. The tester then operates the starter and observes its performance. This allows for the identification and rectification of any potential issues before the motor starter is installed, reducing the risk of failure or malfunctions once in operation.

Bench testing serves as a proactive measure to ensure the reliability and safety of the motor starter. It confirms that the starter can safely and efficiently control the motor’s operation, assuring that it will perform as expected when installed in its intended application.

Why Bench Testing is Crucial for Motor Starters

Bench testing is a vital step in the deployment of motor starters for several reasons.

  1. Ensures Functionality: Bench testing allows for a thorough check of the motor starter’s functionality. It verifies that the starter can correctly start and stop the motor and that protective features like overload relays are functioning as they should.
  2. Identifies Potential Issues: By testing the motor starter in a controlled environment, any potential problems can be identified and rectified before installation. This proactive approach reduces the risk of subsequent operational issues and potential downtime.
  3. Reduces Installation Errors: Bench testing can also help prevent installation errors. By familiarizing themselves with the motor starter’s operation during the test, technicians can ensure a smoother and more accurate installation process.
  4. Saves Time and Costs: By identifying and solving potential issues before installation, bench testing can save considerable time and costs associated with troubleshooting and rectifying problems in installed systems.

In summary, bench testing is an essential step in ensuring the reliability and efficiency of motor starters, thereby contributing to the overall safety and effectiveness of industrial operations.


After understanding the importance of motor starters in industrial applications, it’s valuable to delve deeper into the practical aspects of their usage. One of the key steps before installing a motor starter is bench testing.

Our video tutorial, “Bench Testing a NEMA Size 4 Motor Starter,” provides an in-depth guide on this process, offering practical insights and step-by-step instructions. We encourage you to watch this video and deepen your understanding of motor starters and the bench testing process. Your journey towards mastering motor starters continues there.