The repulsion motor starting method involves a unique approach to start a single-phase motor which is specially designed with a repulsion mechanism. This type of motor uses brushes and a commutator similar to those found in a DC motor, but it operates on AC power. Here is what happens during the starting process:

1. Brush Contact: Initially, the brushed are short-circuited and in direct contact with the commutator segments. Unlike in operation, where they may be lifted or in specific positions for optimal performance, at startup, their full engagement is crucial.

2. Application of AC Voltage: When AC voltage is applied to the stator of the motor, a magnetic field is generated. This magnetic field induces a current in the rotor through the commutator and brush assembly.

3. Magnetic Repulsion: As the currents flow through the rotor’s windings, they interact with the stator’s magnetic field. This interaction is governed by the law of electromagnetic induction and leads to a repulsion that causes the rotor to turn. The specific direction of rotation is determined by the brush positioning relative to the stator field.

4. Rotor Movement: The initial movement of the rotor is due to the repulsion between the magnetic fields of the stator and those induced in the rotor windings. This repulsion force is strongest at the start, providing the necessary torque to overcome inertia and start the motor.

5. Speed Regulation & Transition to Operation: As the

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.