What is Repulsion Motor: Types, Structure, Working Principle

Hello friends, today I am going to tell you What is repulsion motor, Structure of repulsion motor, Type of repulsion motor, Working principle of repulsion motor, Characteristics of repulsion motor.  : If you also want to know, then keep reading this article completely.

What is Repulsion Motor

The repulsion motor is a separate existing motor. In this, the direction of rotation is changed by changing the position of the carbon brushes, i.e., the armature region is polar in its design. Suppose the armature is short-circuited and the short-circuited coil is placed in a magnetic field formed by supplying a phase alternating current to the field pole. In that case, equal poles are included in the armature coil and the field pole opposite to each other. N is next to the north pole, and S is the s pole in front of the south pole. These poles repulse and rotate the rotor. Thus these motors are called repulsion motors.

Structure of repulsion motor

The design of the repulsion motor also consists of two parts
(1) stator part
(2) rotor part

The repulsion motor consists of a wound rotor and stator. The stator winding is like the primary winding of a simple one-phase induction motor; its rotor structure is D.C. It is like the rotor of a machine, but in this, the brushes are moving on the surface of the commutator. The stator coil is connected to the A.C. supply. Hence it is kept along the stator pole or perpendicular to this axis.

Type of repulsion motor

There are three types of these motors
(i) plain repulsion motor
(ii) repulsion induction motor
(iii) repulsion starting induction motor

(i) Plain Repulsion Motor – As in Figure 1, the stator of a plain repulsion motor is usually two-pole and coiled for alternating current single-phase supply. Its rotor is generally made like the armature of a D.C. motor. The rotor carbon brushes mounted in the armature or the rotor are short-circuited. This causes the opposite ends of the converter to be shortened. The position of the carbon brushes is kept 20° ahead of the axis of the field poles.

The speed of this motor depends on the position of the carbon brushes; at 20°, this motor has a maximum speed.

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(ii) Repulsion Induction Motor – In this motor, the winding of the stator is done like that of an induction motor. In the rotor, one winding is done by cage type, and the other coil is by S-E wire whose ends are connected to the commutator. Its structure is shown in Figure 2.

Initially, the cage-type coil does not generate any torque when the motor is started due to high reactance. In this case, the engine starts as a repulsion motor. When the speed gradually increases, the effect of cage type coil increases, and this motor remains at a constant rate on induction load at this time. This motor can be directly connected to the supply.

To keep the efficiency of this motor high, the auxiliary coil is separated from the stator. It is attached separately to two-carbon brushes mounted on the converter. The motor unit operates on the power factor because the wear and tear are negligible.

(iii) Repulsion Start Induction Run Motor- Repulsion Start Induction Run Motor will start like a repulsion motor as per the name but run like an induction motor.

In this motor, a unique copper ring is installed near the converter. This short circuit ring sticks to the whole convertor at 75% speed and short circuits the segment. The conductors of the rotor also get short-circuited. The motor operates as an induction motor. The centrifugal switch is shown in Figure 3, which openly affixes the ring to the commutator with centrifugal force, and when the motor is turned off, the ring is again removed from the commutator.

When the motor starts, it works like a repulsion motor and gives good torque in the beginning, and when the short-circuited ring short circuits the converter at 75 percent speed, it starts running like an induction motor. In this motor, the direction of rotation can also be changed by changing the direction of the carbon brushes.

Working principle of repulsion motor

This motor works on the principle of generating torque due to the repulsive force between equal poles.
When the brush axis is placed at some angle from the field axis, poles of equal polarity are produced on the armature. There is a force of repulsion between the stator pole and the armature pole of the same pole. Due to which the rotation of the rotor occurs in the same direction in which the brush is displaced.

Characteristics of repulsion motor

The characteristic curves of a repulsion motor are shown in Fig. 4.

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what did you learn today:-

What is Repulsion Motor, Structure of repulsion motor, Type of repulsion motor, Working principle of repulsion motor, Characteristics of repulsion motor.