Hello friends, today I am going to tell you that Operation Principle of Schrage Motor, what is Schrage motor?, Characteristics of Schrage Motor, uses of Schrage motor.
what is Schrage motor?
Schrage motor is a special structured three wheel motor whose characteristics are similar to that of dc shunt motor. The speed and power multiplier of this motor can be controlled simultaneously.
Features of the design of the Schrage motor
The design features of the Schrage motor are as follows
1.Schrage motor has provision for both speed control and power factor correction.
2.In the induction motor, the slip regulator is installed in the motor itself.
3.There are three types of windings, which are as follows.
(i) Primary winding- It is housed at the bottom of the rotor slots and is supplied by slip-rings and brushes at line frequency.
(ii) Regulating Winding- It is also called as Compensating Winding or Tertiary Winding and is also called as D.C. Like the armature of the motor, it is connected to the commutator.
(iii) Secondary winding- It is mounted in the stator slots but the end of each phase winding is connected to a pair of brushes mounted on the commutator. These brushes are mounted on two separate brush rockers which are designed to move in the opposite direction from the central line corresponding to the stator phase.
2.Speed Control- Schrage motor is easy to operate at high or low speed with synchronous speed. As shown in Figure 2(i), when the brush pair is connected to the same commutator segment, the secondary winding short circuits and the machine operates like an inverted plane squirrel-cage induction motor with low positive slip . Splitting the brushes in one direction results in subsynchronous speeds as shown in Figure 2(ii) because in this case the regulating voltage of the secondary winding opposes the voltage generated by the primary winding. However, when the brushes are reversed, they split in the opposite direction, the direction of the regulating voltage reverses and the motor speed attains a higher synchronous (max) value as shown in Fig. 2(iii) According). The commutator provides the maximum voltage when the brushes are separated by a pole pitch.
The maximum and minimum speeds are obtained by varying the magnitude of the regulating voltage. The speed can be changed up to twice the zero synchronous speed by the Schrage motor.
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Operation Principle of Schrage Motor
The speed of an induction motor depends on the total electromotive force acting in the secondary circuit i.e. the rotor. If the secondary rotor coil is short-circuited normally, the emf produced in the rotor will be the induced emf and the motor will operate at normal speed. Now if an electromotive force is injected into the rotor circuit from a source of appropriate frequency, then if the component of this injected emf is exactly opposite to the induced emf, then the speed of the induction motor will be less than the normal speed. . Conversely, if the component of the injected EV is in the phase of the component of the induced EV, then the total EM of the secondary or rotor circuit will increase, making the speed of the induction motor higher than the normal speed. In addition, if the right-angled component of the injected electromotive force is ahead of the induced rotor electromotive force, the power factor of the motor will improve.
The commutator of the Schrage motor is mounted on a 6-brush set or 3 pairs of brush sets as shown in Figure 3, and each phase winding of the secondary winding is connected to a pair of brushes. Brushes al, an and a are mounted on a brush spider movable at 120° from each other and similarly brushes b1, b and by are also mounted on another movable brush spider at 120° from each other.
Thus two pairs of brushes are arranged on the converter in such a way that all the brushes can be rotated around the commutator jointly. The frequency of the electromotive force injected into the secondary or stator coil depends on the displacement of the two brush pairs. Thus the speed and power factor of the Schrage motor can be controlled by changing the position of the spiders of the movable brushes. The speed of the motor depends on the displacement between the brush pairs alone, while the power factor depends on the angular displacement of the brushes combined.
Characteristics of Schrage Motor
The rotor speed and separation are shown in Figure 4(i) and the curves between torque and speed are shown in Figure 4(ii).
uses of Schrage motor
(i) In the printing press as electricity conduction.
(ii) In textile mills.
(iii) in a centrifugal pump.
(iv) Hosiery fittings and spinning machines.
(v) In machine packaging.
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what did you learn today:-
Today you learned about the Operation Principle of Schrage Motor, what is Schrage motor?, Characteristics of Schrage Motor, uses of Schrage motor.