Category: Induction Machine

Starting Induction Motor

Starting Induction Motor: At the time of Starting Induction Motor slip being unity, the load resistance with reference to the approximate circuit model of Fig. 9.23 ismeaning thereby that short-circuit conditions prevail. Therefore, the motor current at starting can be as large as five to six times the full-load current. In comparison the exciting current […]

Circuit Model Parameters

Tests to Determine Circuit Model Parameters Circuit Model Parameters – As the Circuit Model Parameters of an induction motor is similar to that of a transformer, the parameters of the model can be obtained by means of nonloading tests as in the case of the transformer—no-load test (corresponding to the OC test on the transformer) and the […]

Torque Slip Characteristic

Torque Slip Characteristic: The expression for Torque Slip Characteristic (T(s)) is easily obtained by finding the Thevenin equivalent of the circuit to the left of ab in Fig. 9.12. The circuit then reduces to Fig. 9.13 in which it is convenient to take VTH as the reference voltage. Equation (9.22) is the expression for torque […]

Power Across Air Gap Torque Power Output

Power Across Air Gap Torque Power Output: Power Across Air Gap Torque Power Output – The circuit model of Fig. 9.7(e) is redrawn in Fig. 9.10. The power crossing the terminals ab in this circuit is the electrical power input per phase minus the stator loss (stator copper-loss and iron-loss) and hence is the power […]

Approximate Circuit Model

Approximate Circuit Model: An Approximate Circuit Model of an induction motor, which results in considerable computational ease in analysis, is obtained by shifting the shunt branch in Fig. 9.8(a) to the input terminals as shown in Fig. 9.9. This step is not so readily justified as in a transformer owing to the relative magnitude of the […]

Development of Circuit Model

Development of Circuit Model(Equivalent Circuit): Development of Circuit Model – As we shall be mostly dealing with phasor magnitudes the superbar on phasor symbols would only be used for phasor equations.In Sec. 9.3 the behaviour of the induction machine was studied in terms of the basic field phenomenon. The attempt here was purposely focussed on […]

Principle of Operation of Induction Motor

Principle of Operation of Induction Motor: The Principle of Operation of Induction Motor Figure 9.4 shows the cross-sectional view of an induction motor. The stator is fed from a 3-phase supply of voltage V/phase and frequency f Hz. The rotor is wound* 3-phase for as many poles as the stator and is short-circuited. It is […]

Construction of Induction Motor

Construction of Induction Motor: The stator of an Construction of Induction Motor is similar to that of a synchronous machine and is wound for three phases, modem practice being to use the two-layer winding. Figure 9.1 shows the stator of an induction motor. Two types of constructions are employed for the rotor wound-rotor and squirrel-cage […]

Introduction to Induction Machine

Introduction to Induction Machine: The Introduction to Induction Machine is an important class of electric machines which finds wide applicability as a motor in industry and in its single-phase form in several domestic applications. More than 85% of industrial motors in use today are in fact induction motors. It is substantially a constant-speed motor with […]