The repulsion motor starting method is typically used in a specific type of single-phase electric motor known as a repulsion motor. This method leverages the repulsive forces between the brushes and the commutator segments that are momentarily short-circuited to initiate the motor’s rotation. The primary scenarios where the repulsion motor starting method finds application include:

1. High Starting Torque Requirements: It is particularly chosen for applications where a high starting torque is essential. The unique construction and starting mechanism of repulsion motors provide superior starting torque compared to other types of single-phase motors.

2. Intermittent or Heavy Loads: Due to their robust starting torque and ability to handle heavy loads, repulsion motors (and thus, the repulsion motor starting method) are ideal for machinery that operates under heavy or intermittent loads, such as cranes, lifts, and certain types of printing presses.

3. Applications Requiring Speed Control: Although less common in modern applications due to the advent of variable frequency drives (VFDs) and other advanced speed control technologies, repulsion motors historically found use in applications requiring variable speed, as their speed can be adjusted by shifting the brushes.

It’s important to note that despite the advantages, the use of repulsion motors has decreased over time, with many applications now favoring more modern and efficient motor designs. However, the repulsion motor starting method remains an interesting concept in electrical engineering, showcasing the diversity of motor starting techniques developed to address specific operational

The shaded pole starting method is primarily utilized in single-phase induction motors, particularly in small, low-power applications such as fans, blowers, desk fans, and toys. This method relies on creating a rotating magnetic field with the help of a shaded pole to initiate motor rotation. Here’s a step-by-step explanation of what happens according to the displacement in the shaded pole starting method:

1. Construction of the Shaded Pole Motor: In the shaded pole induction motor, one side of each pole is wrapped with a short-circuited, copper coil called a “shading coil.” This shaded portion of the pole creates a delayed magnetic field in relation to the unshaded part.

2. Magnetic Field Displacement: When alternating current (AC) is supplied to the stator winding, a magnetic field is produced. This field is divided into two parts due to the presence of the shading coil. The flux in the shaded part of the pole lags behind the flux in the unshaded part because the induced current in the shading coil opposes the change in flux according to Lenz’s law.

3. Creation of a Rotating Magnetic Field: The difference in flux strengths between the shaded and unshaded parts of the pole causes a rotating magnetic field. This field is relatively weak but sufficient to start the rotor turning. The displacement in the magnetic field across the pole, from the unshaded to the shaded part, provides the necessary phase difference that creates a rotating magnetic field

The starting winding in a split phase motor is cut out of the circuit once the motor reaches a certain speed, typically between 70% to 80% of its full operating speed. This action is usually accomplished through a centrifugal switch or a relay that opens when the motor reaches the said speed, disconnecting the starting winding.

The displacement between the running and the starting (auxiliary) windings in a single-phase induction motor is typically 90 electrical degrees. This phase displacement allows the motor to generate a rotating magnetic field, which is necessary for starting and running the motor. By having the windings displaced by 90 degrees, the motor can produce a more balanced torque, aiding in its starting and improving its efficiency during operation. The starting winding is often engaged with the help of a centrifugal switch or an electronic controller and is disconnected once the motor reaches a certain speed.

For self-starting a single-phase induction motor, there are primarily three methods used:

1. Split-phase induction motor method: In this method, the stator is equipped with two windings – a main winding and an auxiliary winding. The auxiliary winding, which has a higher resistance than the main winding, creates a phase difference in the magnetic field to start the motor. Once the motor reaches a certain speed, a centrifugal switch or electronic controller disconnects the auxiliary winding.

2. Capacitor start motor method: Similar to the split-phase motor, this method uses a capacitor in series with the auxiliary winding to create a greater phase difference between the currents in the main and auxiliary windings. This increases starting torque compared to a split-phase motor. The auxiliary winding and capacitor are disconnected from the circuit once the motor reaches around 75-80% of its rated speed, typically using a centrifugal switch.

3. Capacitor start-capacitor run motor method: This method employs two capacitors: a start capacitor and a run capacitor. The start capacitor is used only during the start-up phase to increase starting torque, while the run capacitor remains connected to the auxiliary winding during operation, improving the motor’s efficiency and torque characteristics. This approach provides better performance than the capacitor start motor and the split-phase motor methods.

These are the basic methods commonly used to make single-phase induction motors self-starting. Each method has its unique advantages and is chosen based on the specific requirements of