AC motors include three main types: series motors, synchronous motors, and induction motors. A split-phase motor uses a centrifugal switch to disconnect the starting winding when it reaches about 75% of full speed. The stator is the stationary part that converts electrical energy into mechanical energy for the motor’s operation.
Studying with flashcards enables users to grasp complex ideas more easily. Each card features a question or concept on one side, with a clear explanation or answer on the other. This structure supports self-paced learning and provides immediate feedback. Users can easily track their progress and identify areas needing further review.
Mastering AC motor circuits is essential for professionals and enthusiasts in electrical engineering. Understanding the principles behind AC motors allows for effective troubleshooting and system design. Furthermore, mastering this knowledge can lead to increased efficiency in various applications, from industrial automation to consumer electronics.
Now that you recognize the importance of mastering AC motor circuit knowledge, let’s delve deeper into the essential components of motor control circuits. We will explore the various types of AC motors, their operational principles, and how to effectively control them.
What Is an AC Motor Circuit and Why Is It Important for Motor Control?
An AC motor circuit is an electrical network specifically designed to control alternating current (AC) motors. This circuit facilitates motor operation through components such as power supply, control devices, protection devices, and load connections.
According to the Institute of Electrical and Electronics Engineers (IEEE), AC motor circuits enable the effective control and operation of AC motors in various applications. These circuits can manage both motor speed and torque, enhancing performance efficiency.
AC motor circuits operate by converting electrical energy into mechanical energy while ensuring safe and reliable motor performance. Key aspects include the power source, control methods like variable frequency drives, and protection mechanisms that prevent overcurrents and short circuits.
The National Electrical Manufacturers Association (NEMA) also defines AC motor circuits as vital for automated processes and industrial control systems, highlighting their significance in operational reliability.
Various factors contribute to the importance of AC motor circuits, including increased energy efficiency requirements and the growing reliance on automation technologies. Efficient motor control can lead to reduced energy costs and improved production rates.
About 45% of global electricity consumption comes from electric motors, according to the International Energy Agency (IEA). This figure indicates a substantial opportunity for improved motor circuit efficiency to enhance energy savings and environmental impact.
Effective AC motor circuits lead to better operational reliability, which can improve product quality and reduce downtime in industrial processes, benefiting various sectors.
The societal impact of efficient AC motor circuits includes lower operational costs, better resource management, and enhanced energy sustainability. Economically, they contribute to significant savings in energy expenses for industries.
Specific examples of these impacts include manufacturing plants that reduce production costs through efficient motor controls or renewable energy facilities benefiting from optimized energy use.
To address challenges in AC motor circuit applications, promoting smart technologies and advanced control systems is crucial. Organizations like the U.S. Department of Energy advocate for implementing energy-efficient practices.
Strategies such as leveraging variable frequency drives, predictive maintenance, and energy optimization programs can help businesses achieve better motor control efficiency and sustainability.
What Are the Key Components of an AC Motor Circuit?
The key components of an AC motor circuit include several essential elements that work together to ensure the motor operates effectively.
- Power Supply
- AC Motor
- Starter
- Control Circuit
- Protection Device
- Capacitor (for specific motor types)
- Wiring and Connectors
The components mentioned contribute to the overall function of the AC motor circuit in various ways. This creates a foundation for understanding how each part interacts within the system.
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Power Supply:
The power supply provides the electrical energy necessary for the operation of the AC motor. In most cases, this source is an alternating current (AC) source from the electrical grid. Acquiring the right voltage level is critical for efficient motor function. For instance, a standard industrial motor usually operates at 230V or 460V AC. -
AC Motor:
The AC motor is the primary component that converts electrical energy into mechanical energy. This happens through electromagnetic induction. AC motors can be categorized into synchronous and asynchronous (induction) motors. Synchronous motors operate at a constant speed, while induction motors operate at a speed that is lower than the synchronous speed. -
Starter:
A starter, such as a contactor or relay, is used to manage the starting and stopping of the motor. Starters help prevent damage by limiting the initial surge of current, which can be detrimental to the motor. This can include soft starters or variable frequency drives, which adjust the voltage and frequency for a smoother start. -
Control Circuit:
The control circuit serves to manage the operation of the motor. It includes switches, relays, and timers that allow for automation in starting, stopping, or adjusting the speed of the motor. This circuit ensures efficient operation and can be configured to allow remote control capabilities. -
Protection Device:
Protection devices, such as fuses or circuit breakers, are included to safeguard the circuit and motor from faults. They disconnect power during overloads or short-circuits, thereby preventing damage. Selecting the correct rating is crucial for ensuring maximum protection. -
Capacitor (for specific motor types):
In capacitor-start or capacitor-run motors, capacitors provide an additional phase shift that enhances efficiency and performance. These components create a secondary winding to help generate starting torque. Proper sizing is important to optimize motor performance. -
Wiring and Connectors:
Proper wiring and connectors ensure the reliable transmission of electrical power to the motor. This aspect involves choosing wires with the appropriate gauge and insulation to handle the motor’s current load, thus preventing overheating or failures.
Understanding these components helps in diagnosing issues, planning installations, and ensuring safe operations within AC motor circuits.
How Does Each Component Contribute to Circuit Functionality?
Each component of a circuit contributes to its overall functionality in distinct ways. A power source provides the necessary energy for the circuit to function. Wires allow for the efficient transfer of electrical energy between components. Resistors control the flow of current, ensuring that each part of the circuit receives the appropriate level of voltage. Capacitors store and release energy, helping to smooth out fluctuations in current and voltage. Inductors store energy in a magnetic field and can influence the timing of the current flow.
Switches enable the opening and closing of circuits, allowing users to control the flow of electricity. Diodes allow current to flow in one direction only, protecting sensitive components from back currents. Transistors act as switches or amplifiers, regulating the flow of current and thereby controlling circuit behavior. Together, these components interact to create a functional circuit, where each part plays a critical role in determining how the entire system operates.
What Are the Main Types of AC Motors Used in Circuits?
The main types of AC motors used in circuits are as follows:
- Synchronous Motors
- Induction Motors
- Universal Motors
- Stepper Motors
- Servo Motors
Each type of AC motor has unique characteristics and applications. Understanding these differences helps in selecting the right motor for specific needs.
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Synchronous Motors:
Synchronous motors run at a constant speed proportional to the frequency of the alternating current supply. The motor’s rotor rotates in synchrony with the stator’s rotating magnetic field. This type of motor is known for its efficiency and ability to maintain speed under varying loads. According to a study by the Electric Power Research Institute, synchronous motors often achieve efficiencies above 95%. These motors are commonly used in applications requiring precise speed control, such as in synchronous condensers and large industrial drives. -
Induction Motors:
Induction motors are the most widely used AC motors in the world. They do not require any external power source to the rotor, making them reliable and cost-effective. In these motors, current is induced in the rotor by the rotating magnetic field produced by the stator. The National Electrical Manufacturers Association states that approximately 75% of all electric motors sold in the U.S. are induction types. They are commonly found in fans, pumps, and household appliances due to their robustness and low maintenance requirements. -
Universal Motors:
Universal motors can operate on both AC and DC power sources. They are series-wound motors that provide high starting torque, making them suitable for applications requiring intermittent operation, such as power tools and kitchen appliances. A review by the IEEE states that these motors are less efficient than induction motors but are favored in portable equipment due to their lightweight and compact design. -
Stepper Motors:
Stepper motors convert electrical pulses into discrete mechanical movements. They provide precise positioning and control, which is essential in applications such as 3D printing and robotic systems. These motors are used in computer drives and CNC machines due to their ability to accurately control speed, position, and acceleration. A study from the Journal of Mechanical Engineering Technology highlights that stepper motors offer high reliability and repeatability, making them ideal for automation scenarios. -
Servo Motors:
Servo motors are used in applications that require precise control of angular position and speed. They typically include a feedback device, allowing for fine adjustments. These motors are prevalent in robotics, conveyor systems, and CNC machinery. According to research by the Society of Automotive Engineers, servo motors give better performance in terms of acceleration and speed control compared to other motors. They are suitable for applications demanding high precision and performance.
Understanding these types of AC motors enables better decision-making in selecting appropriate motors for various applications, ensuring efficiency and effectiveness in their functions.
How Do Induction and Synchronous AC Motors Differ in Operation?
Induction and synchronous AC motors differ primarily in how they operate to create rotational motion, focusing on rotor design and interaction with the magnetic field.
Induction Motors:
– Rotor Design: Induction motors have a rotor that does not require any external power supply. It relies on electromagnetic induction, where the rotor is magnetized by the rotating magnetic field generated by the stator.
– Slip: These motors operate with a phenomenon called “slip.” Slip refers to the difference in speed between the rotating magnetic field and the rotor speed. A small slip is necessary for torque generation.
– Starting: Induction motors are known for their simple construction and ease of starting. They can start directly under load without the need for additional starting mechanisms.
– Efficiency: They typically have lower efficiency and power factor ratings than synchronous motors. According to the International Electrotechnical Commission (IEC), induction motors can average efficiencies around 85-95%.
Synchronous Motors:
– Rotor Design: Synchronous motors contain a rotor that is designed to rotate at the same speed as the magnetic field produced by the stator. The rotor is usually equipped with either permanent magnets or electromagnets.
– Constant Speed: These motors achieve constant speed under varying loads, as they synchronize with the power supply frequency. This characteristic is beneficial in applications requiring precision.
– Starting: Synchronous motors often require additional starting mechanisms, such as variable frequency drives (VFDs) or auxiliary motors, to reach synchronization speeds.
– Efficiency: They tend to be more efficient, often exceeding 90%. Studies by the American Electric Power Research Institute (AEPRI, 2020) indicate that synchronous motors can provide better power factor performance, which can contribute to lower energy costs.
In summary, the key differences between induction and synchronous AC motors lie in their rotor operation, efficiency levels, and starting mechanisms, which ultimately affect their applications in industrial and commercial settings.
What Basic Principles Should You Understand for AC Motor Control?
The basic principles to understand for AC motor control include operational principles, types of AC motors, control methods, and safety considerations.
- Operational Principles of AC Motors
- Types of AC Motors
- Control Methods for AC Motors
- Safety Considerations in AC Motor Control
The following will explore each principle in detail, emphasizing their importance in AC motor control.
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Operational Principles of AC Motors: Understanding the operational principles of AC motors is essential. AC motors run using alternating current, which reverses direction periodically. This change in current creates a rotating magnetic field. The interaction between this field and the rotor induces motion. The rotating magnetic field aligns with the windings, allowing the motor to convert electrical energy into mechanical energy efficiently.
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Types of AC Motors: AC motors can be classified mainly into two types: synchronous and asynchronous (or induction) motors. Synchronous motors operate at a constant speed in sync with the supply frequency. They require an external DC supply for excitation. Induction motors are more common and operate on the principle of induced current. Their rotor speed is always less than the magnetic field speed, enabling easier design and maintenance.
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Control Methods for AC Motors: Control methods include varying frequency drives (VFDs), which adjust the motor speed by changing the frequency of the electricity supplied. VFDs increase efficiency and enhance operational flexibility. Other methods include direct on-line (DOL) starting, star-delta starting, and soft starters, which manage torque and reduce electrical stress during startup.
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Safety Considerations in AC Motor Control: Safety in AC motor control involves implementing protective devices like overload relays, circuit breakers, and fuses. These devices prevent equipment damage and ensure safety by cutting off current in overload situations. Understanding electrical codes and regulations is important to ensure compliance and avoid electrical hazards.
By grasping these basic principles, one can effectively manage AC motor operations while ensuring efficiency and safety.
How Can Flashcards Enhance Your Understanding of AC Motor Circuits?
Flashcards enhance your understanding of AC motor circuits by promoting active recall, facilitating spaced repetition, encouraging self-assessment, and enabling the organization of complex concepts. These techniques can significantly bolster retention and comprehension.
Active recall: Flashcards stimulate active recall by prompting you to retrieve information from memory. A study by Roediger and Butler (2011) highlights that this retrieval practice strengthens memory retention better than passive review methods. Engaging with questions on flashcards forces your brain to retrieve concepts related to AC motors, such as phase relationships and rotor functionality.
Spaced repetition: Flashcards utilize spaced repetition, where information is reviewed at increasing intervals. Ebbinghaus’s forgetting curve illustrates the retention benefits achieved by revisiting material over time. For instance, concepts like stator windings and electromagnetic principles can be reinforced through timely reviews, leading to deeper understanding.
Self-assessment: Flashcards allow for self-assessment and immediate feedback. When you test your knowledge about AC motor components like capacitors or inductors using flashcards, you can quickly identify areas requiring more study. This helps in diagnosing knowledge gaps and focusing your learning efforts effectively.
Organization of complex concepts: Flashcards can break down complex ideas into manageable pieces. Each card can cover specific attributes of AC motor circuits, such as voltage types or power factor. This organization helps build a solid foundation of understanding by connecting smaller concepts to broader topics, ultimately creating a clearer mental framework.
By employing these strategies, flashcards serve as an effective tool for enhancing comprehension and retention of AC motor circuits, enabling better learning outcomes.
What Common Problems Might You Encounter in AC Motor Circuits?
The common problems you might encounter in AC motor circuits include electrical faults, mechanical issues, and control system failures.
- Electrical Faults
- Mechanical Issues
- Control System Failures
- Overheating
- Insulation Breakdown
Understanding these problems is crucial for effective troubleshooting and maintenance.
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Electrical Faults: Electrical faults in AC motor circuits often involve issues like short circuits, open circuits, and phase loss. A short circuit occurs when an unintended path creates a low-resistance pathway, potentially damaging components. Open circuits can happen due to a broken connection, causing the motor to stop functioning entirely. Phase loss refers to the absence of one or more supply phases, leading to imbalanced operation and overheating. According to a study by B. G. P. Gomes in 2019, electrical faults account for over 30% of motor failures in industrial applications.
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Mechanical Issues: Mechanical issues affect the hardware of AC motors and may involve bearing failures, misalignment, or excessive vibration. Bearing failure can lead to increased friction, heat generation, and motor breakdown. Misalignment occurs when the motor shaft does not align properly with the driven equipment, causing uneven wear and tear. Excessive vibration can damage critical components. The National Electrical Manufacturers Association (NEMA) notes that mechanical problems contribute to about 40% of motor-related failures.
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Control System Failures: Control system failures in AC motors can stem from faulty components, inappropriate settings, or programming errors. A malfunctioning variable frequency drive (VFD) can cause incorrect motor speeds or malfunction. Setting the wrong parameters in the motor control can lead to inefficiencies. A case study by D. Smith in 2021 highlights that 25% of downtime in industrial settings is linked to control system issues in AC motors.
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Overheating: Overheating in AC motors typically arises from overload conditions or insufficient cooling. An overload happens when a motor operates beyond its rated capacity, generating excessive heat. Lack of proper cooling, due to blocked air filters or inadequate ventilation, can exacerbate the heating issue. Overheating can result in irreversible damage to motor insulation, leading to costly repairs. The American Society of Mechanical Engineers (ASME) identifies overheating as a prevalent issue contributing to about 15% of motor failures.
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Insulation Breakdown: Insulation breakdown occurs when the electrical insulation between the motor windings deteriorates. Factors leading to breakdown include aging, overheating, moisture intrusion, and mechanical stress. The consequences include short circuits and motor failure. The IEEE reports that insulation failure accounts for 30% of AC motor failures. Regular maintenance and testing can mitigate this risk and prolong motor life.
By recognizing and addressing these common problems, one can greatly improve the reliability and longevity of AC motor circuits.
What Are Effective Troubleshooting Techniques for AC Motor Issues?
Effective troubleshooting techniques for AC motor issues include a systematic approach to identify and resolve problems efficiently.
- Visual Inspection
- Electrical Testing
- Vibration Analysis
- Thermal Imaging
- Isolation of Components
- Review Operating Conditions
- Consult Manufacturer Documentation
These techniques enable technicians to pinpoint issues accurately, but opinions on their effectiveness may vary based on the context and experience level of the technician. Some experts may argue that relying too heavily on technology, such as thermal imaging, can overlook simple, common issues. Transitioning into more detail, exploring each technique will provide a comprehensive understanding of their relevance in troubleshooting AC motor issues.
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Visual Inspection:
Visual inspection involves examining the AC motor for any obvious signs of damage or wear. Technicians check for loose connections, damaged insulation, or physical obstructions around the motor. According to a study by the IEEE in 2020, about 30% of motor failures can be traced back to visible issues like misalignment or corrosion. Regular visual checks can prevent substantial damage and are often the first step in troubleshooting. -
Electrical Testing:
Electrical testing includes measuring voltage, current, and resistance in the motor circuit. Common tools used are multimeters and clamp meters. For instance, measuring current can help identify overloads, while voltage drops may indicate wiring problems. According to the National Electrical Manufacturers Association (NEMA), improper electrical conditions cause more than 50% of AC motor failures. Electrical testing provides critical data for accurate assessments. -
Vibration Analysis:
Vibration analysis evaluates the mechanical condition of an AC motor. It involves monitoring vibration patterns using specialized sensors. Changes in vibration signature can indicate issues such as imbalance, misalignment, or bearing problems. A report by the Machinery Failure Prevention Tech Team emphasizes that regular vibration analysis can reduce unexpected failures by up to 50%. It is essential in predictive maintenance programs. -
Thermal Imaging:
Thermal imaging uses infrared cameras to identify overheating components in motors. Elevated temperatures can indicate electrical faults, friction, or insufficient lubrication. A study from the Lawrence Berkeley National Laboratory found that thermal imaging can detect issues before they become severe, reducing maintenance costs by approximately 30%. Its non-invasive nature allows for efficient monitoring without disrupting operations. -
Isolation of Components:
Isolation of components involves disconnecting the motor from other system parts to identify where an issue originates. This technique helps in distinguishing whether the problem lies within the motor itself or the connected systems. For instance, checking the power supply separately can rule out external electrical issues. A case study published in the Journal of Quality in Maintenance Engineering showed that isolating components led to quicker troubleshooting times by 40%. -
Review Operating Conditions:
Reviewing operating conditions assesses whether an AC motor operates within its specified parameters. Factors include load, temperature, and humidity. Non-compliance with recommended conditions can lead to premature failure. The American Society of Mechanical Engineers (ASME) highlights that nearly 60% of motors failed due to improper operating conditions. Maintaining optimal conditions enhances reliability and longevity. -
Consult Manufacturer Documentation:
Consulting manufacturer documentation includes reviewing technical manuals, wiring diagrams, and troubleshooting guides. These resources provide valuable information specific to the motor model. According to a maintenance report by the National Institute for Occupational Safety and Health (NIOSH), referencing documentation can improve troubleshooting efficiency by 25%. Access to accurate information ensures proper procedures are followed during repairs.
By understanding these methods, technicians can enhance their troubleshooting abilities and effectively address AC motor issues.
What Essential Knowledge Should You Master for the AC Motor Circuit Quiz?
To excel in the AC Motor Circuit Quiz, you should master fundamental concepts of AC motors and their circuits, including operation principles, components, and safety measures.
Key Knowledge Areas:
1. Basic principles of AC motors
2. Components of AC circuits
3. Types of AC motors
4. Motor control methods
5. Electrical safety protocols
Understanding these topics can significantly enhance your readiness for the quiz.
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Basic Principles of AC Motors:
Mastering the basic principles of AC motors involves understanding how alternating current generates magnetic fields. AC motors convert electrical energy into mechanical energy. The interaction between the magnetic field and current produces torque to turn the motor shaft. According to Goetzberger et al. (2019), AC motors are known for their efficiency and durability in industrial applications. -
Components of AC Circuits:
Learning the components of AC circuits is crucial. This includes resistors, inductors, capacitors, and transformers. Each component plays a specific role in circuit functionality. For example, inductors store energy in a magnetic field, while capacitors store energy in an electric field. Understanding their functions and how they interact in a circuit is key to solving AC motor problems. -
Types of AC Motors:
Familiarizing yourself with the types of AC motors is essential. The two main types are synchronous and asynchronous (or induction) motors. Synchronous motors maintain a constant speed proportional to the supply frequency. Meanwhile, induction motors rely on the relative motion of the magnetic field and rotor. According to Tardioli (2021), induction motors are more commonly used due to their simplicity and reliability. -
Motor Control Methods:
Knowing the various motor control methods enhances operational efficiency. Control methods include direct-on-line (DOL) starting, star-delta starting, and variable frequency drives (VFDs). VFDs allow precise control of motor speed and torque by adjusting the frequency of the supply voltage. Research from the IEEE suggests that VFDs can lead to significant energy savings in industrial applications. -
Electrical Safety Protocols:
Understanding electrical safety protocols protects personnel and equipment. Key protocols include lockout/tagout (LOTO) procedures, the use of personal protective equipment (PPE), and adherence to electrical codes and standards. The National Electrical Code (NEC) outlines essential safety requirements, ensuring safe operations in electrical installations. Adhering to these protocols minimizes risks associated with electrical work.
What Are the Most Commonly Asked Questions in AC Motor Quizzes?
The most commonly asked questions in AC motor quizzes typically cover fundamental concepts and practical applications of AC motors.
- What is an AC motor?
- What are the main types of AC motors?
- What is the difference between synchronous and asynchronous motors?
- How does an AC motor work?
- What are the main components of an AC motor?
- What are the advantages and disadvantages of AC motors?
- How do you calculate the speed of an AC motor?
- What are torque and power in AC motors?
- Why are AC motors used in industrial applications?
- What is the role of a capacitor in single-phase AC motors?
Understanding these questions will provide a solid foundation for anyone studying AC motors. Each question explores essential characteristics, functioning principles, and application scenarios of AC motors.
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What is an AC Motor?
An AC motor is an electrical machine that converts alternating current (AC) electrical energy into mechanical energy. These motors are widely used in various applications due to their simplicity, durability, and cost-effectiveness. Common examples include fans, pumps, and conveyor systems. -
Types of AC Motors:
The main types of AC motors are induction motors and synchronous motors. Induction motors operate on the principle of electromagnetic induction while synchronous motors require a constant speed, synchronizing with the electrical supply frequency. -
Difference Between Synchronous and Asynchronous Motors:
Synchronous motors run at a constant speed, matching the supply frequency. In contrast, asynchronous motors, or induction motors, operate at a speed less than the supply frequency. This distinction influences their application in industry. -
How AC Motors Work:
AC motors work by creating a rotating magnetic field using alternating current. The interaction between this magnetic field and the rotor generates mechanical motion. This fundamental mechanism allows them to drive various loads efficiently. -
Main Components of an AC Motor:
AC motors typically consist of three main components: stator (the stationary part), rotor (the rotating part), and housing. The stator creates a magnetic field, while the rotor rotates due to the magnetic field interaction. -
Advantages and Disadvantages of AC Motors:
AC motors have several advantages, including higher efficiency, lower maintenance, and simpler design. However, disadvantages can include the need for variable speed drives in some applications and less control over torque compared to DC motors. -
Calculating the Speed of an AC Motor:
The speed of an AC motor can be calculated using the formula: Speed (RPM) = (120 × Frequency) / Number of Poles. This relationship indicates how supply frequency and number of poles influence motor speed. -
Torque and Power in AC Motors:
Torque is the measure of rotational force produced by the motor, while power is the measure of work done over time. Understanding these two concepts is crucial for selecting the right motor for specific applications. -
Role of AC Motors in Industrial Applications:
AC motors are essential in industrial settings due to their robustness and ability to handle heavy loads. They are used in conveyor systems, pumps, and electric fans, demonstrating their versatility and efficiency. -
Capacitor in Single-Phase AC Motors:
Capacitors are used in single-phase AC motors to create a phase shift in the electric current. This phase shift allows the motor to start and run efficiently, as it provides the necessary starting torque and improves overall performance.