Repulsion Start induction Motor PDF

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Repulsion Start induction Motor GROUP 6: BATHAN,JOD CUYA, KIMBERLY DOTE,KRISTINE MACALINDONG,LEIZEL MANALO,MARJORIE Introduction  Parts of Repulsion Start, Induction Motor  Construction of repulsion induction motor  Operation of repulsion start induction motor  Advantage of Repulsion Motor  Dis...

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Repulsion Start induction Motor leizel macalindong

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Repulsion Start induction Motor

GROUP 6: BATHAN,JOD CUYA, KIMBERLY DOTE,KRISTINE MACALINDONG,LEIZEL MANALO,MARJORIE

Introduction  Parts of Repulsion Start, Induction Motor

 Construction of repulsion induction motor

 Operation of repulsion start induction motor  Advantage of Repulsion Motor

 Disadvantage of Repulsion Motor  Application of Repulsion motors

Repulsion sTart induction motor  This motor starts as a repulsion motor, but normally

run as an induction motor, with constant speed characteristics. It consist,  • One stator • One rotor which is similar to the wire-wound d.c armature • A commutator and • A centrifugal mechanism which short-circuits the commutator bars. .

Parts of repulsion start induction motor  Laminated stator core. This core has one

winding which is similar to the main or running winding of a split-phase motor.  Rotor consisting of a slotted core into which a winding is placed. The coils which make up the winding are connected to a commutator. The rotor core and winding are similar to the armature of a dc motor. Thus, the rotor is called an armature.

Parts of repulsion start induction motor  Centrifugal device. 

a. In the brush-lifting type of motor, there is a centrifugal device which lifts the brushes from the commutator surface at 75 percent of the rated speed. This device consists of governor weights, a short-circuiting necklace, a spring barrel, spring, push rods, brush holders, and brushes. Although high in first cost, this device does save wear and tear on brushes, and runs quietly. ill 3 is an exploded view of the armature, radial commutator, and centrifugal device of the brush-lifting type of repulsion start, induction run motor.

Parts of repulsion start induction motor  b. The brush-riding type of motor also contains

a centrifugal device which operates at 75 percent of the rated speed. This device consists of governor weights, a short-circuiting, necklace, and a spring barrel. The commutator segments are short circuited by this device, but the brushes and brush holders are not lifted from the commutator surface.

Construction of repulsion induction motor

Construction of repulsion induction motor  The stator of this motor is constructed very much like that of a

splitphase or capacitor-start motor, but only run or field windings are mounted inside. End bells keep the armature and shaft in position and hold the shaft bearings.  The armature consists of many separate coils of wire connected to segments of the commutator. Mounted on the other end of the armature are governor weights that move push rods that pass through the armature core. These rods push against a short-circuiting ring mounted on the shaft on the commutator end of the armature. Brush holders and brushes are mounted in the commutator end bell, and the brushes, connected by a heavy wire, press against segments on opposite sides of the commutator .

Operation of repulsion start induction motor  The repulsion-induction motor starts on one principle of

operation and, when almost up to speed, changes over to another type of operation. Very high twisting forces are produced during starting by the repulsion between the magnetic pole in the armature and the same kind of pole in the adjacent stator field winding. The repulsing force is controlled and changed so that the armature rotational speed increases rapidly, and, if not stopped, would continue to increase beyond a practical operating speed. It is prevented by a speed-actuated mechanical switch that causes the armature to act as a rotor that is electrically the same as the rotor in single-phase induction motors. That is why the motor is called a repulsion-induction motor.

ADVANTAGES OF REPULSION START INDUCTION MOTOR  High starting torque.  Low starting current.

 Ability to accelerate a heavy load more rapidly than

high-capacitance dual capacitor motors.

disADVANTAGES OF REPULSION START INDUCTION MOTOR  Requires more maintenance.  More expensive.

 Makes quite a bit of noise on starting.  Causes radio interference when starting.  Cannot be reversed easily.

APPLICATIONS  This type of motor is used for such applications as :   

large air compressors, refrigeration equipment, and large hoists, and is particularly useful in locations where low line voltage is a problem.

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