Motor Control Panel

Motor Starter

See Examples

What is a Motor Starter?

A motor starter is an essential electrical device used to start, regulate, and protect electric motors. When motors are started, they draw high currents, which can cause damage to the motor and the electrical system. A motor starter mitigates this by gradually increasing the motor’s power, thereby minimizing the initial current surge and ensuring a controlled and smooth start. It consists of contactors that enable or disable the electrical connection to the motor, overload protection to protect against excessive currents, and a control circuit to manage the motor’s operation. Motor starters are indispensable in a variety of industries, from manufacturing to transportation, as they guarantee motor performance that is both dependable and safe.

 

Why do we need to connect a Starter with Electrical Motors?

There are numerous reasons why motor starters are essential. Initially, they limit the starting current to prevent damage to the motor and electrical infrastructure. This protection extends the motor’s life and lowers its maintenance expenses. Second, starters facilitate a smooth starting process, reducing mechanical stress on connected machinery and preventing sudden jolts. In addition, starters provide overload protection by automatically disconnecting the motor in the event of excessive currents, thereby preventing potential motor failures. In applications requiring bidirectional motor motion, certain motor starters feature reversing functionality. Motor starters ultimately improve motor operation efficiency, safety, and control.

 

How an industrial motor starter operates and its working principle?

A combination of electromechanical and electronic components enables the operation of an industrial motor starter. The control circuit energizes the main contactor’s coil when the start button is pressed. This connects the motor to the power source by closing the contactor’s main contacts. Overload relays also monitor the motor current. If the current exceeds the permissible limits, the overload relays will trip, disabling the motor. The stop button releases the energy of the control circuit, de-energizing the main contactor and halting the motor. Motor starters utilize auxiliary interlocks to ensure proper sequencing and prevent unsafe operating conditions.

 

Types of Motor Starters:

•      High torque
•      Low torque
•      Slow starting speed
•      High starting speed
•      Combinations of above or time variants based on the connected loads

 

High Torque Motors:

Advantages

Disadvantages

 

  • High-torque motors can generate substantial rotational force, making them ideal for heavy-duty applications and tasks requiring a substantial amount of power output.
  • Motors with a high torque may consume more electricity than motors with a low torque, which may result in higher operational costs.
  • Appropriate for Applications with Varying Loads: Their high torque allows them to handle sudden changes in resistance without stalling, making them ideal for applications with varying loads.
  • Increased Weight and Size: To achieve high torque, these motors frequently feature larger and heavier components, which can affect the equipment or machinery’s overall size and weight.
  • These motors can operate effectively in challenging environments, such as steep inclines or rough terrain, where additional torque is required for smooth operation.
 

 

Low Torque Motors:

Advantages

Disadvantages

  • Low torque motors consume less energy during operation, resulting in lower energy costs.

 

  • Low torque motors may not be suitable for heavy-duty applications that require a substantial amount of rotational force.
  • Due to their lower torque requirements, these motors are typically more compact and lighter, making them suitable for applications with space or weight constraints.
  • These motors may stall or be difficult to start if subjected to sudden increases in load or resistance, necessitating careful handling and control.
  • Smooth Operation at Low Loads: They perform admirably in situations requiring precise control and smooth operation at low loads, such as in robotics and precision machinery.
 

 

Slow Starting Speed:

Advantages

Disadvantages

  • Reduced Mechanical Stress Slow-starting motors provide a gentle and gradual acceleration, thereby reducing the mechanical stress on connected machinery and equipment.
  • Lengthier Startup Time: Slow-starting motors may require additional time to reach their operating speed, which could negatively impact productivity in time-sensitive processes.
  • In applications requiring precise positioning or synchronization, slow-starting motors provide improved control and precision.
  • Limited Applicability for High-Speed Applications: These motors may not be suitable for applications requiring rapid acceleration or operation at high speeds.
  • Lower Starting Current: They consume less current during startup, thereby reducing the strain on power supply systems and enhancing the overall electrical efficiency.
 

 

High Starting Speed:

Advantages

Disadvantages

  • Rapid Acceleration: Motors with a high starting speed reach their operating speed rapidly, making them ideal for time-sensitive processes and applications requiring immediate action.
  • Possibility of Increased Wear: A high starting speed may result in increased mechanical wear on the motor and connected components, thereby potentially shortening the system’s overall lifespan.
  • Dynamic Performance: They excel in applications requiring rapid response and high-speed operation, such as high-speed machining and rapid transportation systems.

  • Higher Starting Current: These motors may require higher starting currents, placing additional strain on the power supply system and necessitating a robust electrical infrastructure.

  • Due to their rapid acceleration, motors with a high starting speed experience less wear during the starting phase. With less deterioration and strain on the motor’s components, maintenance and replacement expenses can be reduced over time.

 

  • Higher Power Demand: During the startup phase, achieving high starting speeds requires a significant amount of power. This increased power demand may place additional strain on the power supply system and necessitate a higher-capacity electrical infrastructure, resulting in higher initial installation costs.

Motor Elements

A typical motor starter would consist of an incoming power connection (Single or three phases) connected to a protection system such as a fuse block or a circuit breaker with or without a locking option, contactor switchgear with an overload relay integrated or separately connected and the power delivery cable terminated directly to the field motor or to intermediate terminal blocks. The probable variation to this would include a soft starter or a variable frequency drive after the contactor.

The control elements would include selector switches such as Auto/ Manual, Local / Remote, and push buttons such as Motor Start/ Stop and Pilot indicators for the status. The actuation of the motor could happen from a controller such as PLC in automatic control schemes. Depending on where the control system (maybe PLC or Motor control relay) is located, the control and monitoring wiring signals such as motor winding temperature/ vibration/ overload/ motor operation status/ motor run forward reverse signals/driven equipment signals may land inside the motor starter panel.
A motor starter panel would include any or more of the various starters listed and include all the isolation, safety, protection, and control signals listed above. Starter panels are engineered units designed specifically for the ratings needed and would be almost ready to function with basic installation.

Note:  Standard market available starters are Direct-On-Line Starter, Star-Delta Starter, Reversing starter, Soft Starter, VFD starter

Options Available

4X Stainless Steel or Fibre Glass Enclosure, Floor Mount Kit, Inner Door for controls, NEMA Style Contactors, Electronic Overloads, Multiple motor control, Duplex pump Control, Automatic Transfer Control, Multi winding/speed motor control, Enclosure Heater, Single Phase Application, Custom Controls, Class1 Div1 or 2 starters in the X-Proof Enclosures and Purge Panels.

EXAMPLES OF MOTOR STARTER