4. Note the readings of voltmeter, ammeter and wattmeter by carefully and fill them in table 1 Table 1: The measured parameters during open circuit test of the induction motor Measurement Parameter VLL Value 7640 IL 0.48A Pl P2 75 W 75W Pinput 5. Take the readings quickly so that the machine does not heat up due to full load copper lossestaking place at this condition. 6. Reduce the voltage to zero and turn the main switch off. Discussion: 1. Draw the circuit diagram of short circuit test using PSIM. Give some explanations 2. What is the value of the slip? (unity) 3. What happened to rotor's resistance? 4. Is the input voltage small or rated during short circuit test? Why? 5. Calculate the RX,X' Theory: For this test, the motor shaft is blocked by your hand so that it cannot turn. The motor terminals are connected to a 3-phase supply. The rotor becomes the secondary of a transformer operating at the supply frequency. So, the blocked rotor test is similar to the short circuit test on a transformer. It is performed to calculate the series parameters of the induction machine i.e., its leakage impedances. The rotor is blocked to prevent rotation and balanced voltages are applied to the stator terminals where the rated current is achieved. Under the reduced voltage condition and rated current, core loss and magnetizing component ofthe current are quite small percent of the total current, equivalent circuit reduces to the form shown in Fig.(1). R1 + M jX1 m Isc jX2' R2' m Vph Fig. 1: Equivalent circuit for blocked rotor test The slip for the blocked rotor test is unity since the rotor is stationary. The resulting speed-dependent equivalent resistance r2' {(1/s)-1} goes to zero and the resistance of the rotor branch of the equivalent circuitbecomes very small. Thus, the rotor current is much larger than current in the excitation branch of the circuitsuch that the excitation branch can be neglected. Voltage and power are measured at the motor input. Experimental Procedure: 1. Connect the circuit as shown in the connection diagram in Figure 2. 11 U O A V No W 12 A 2 > 0 U₁ IM VLL1 T V Shaft VLL2 W Heavy Mechanical Load Fig.2. Short circuit test of induction motor 2. Before starting, ensure that the shaft is blocked completely from rotating. 3. Increase the voltage to the machine such that it draws rated current.

4. Note the readings of voltmeter, ammeter and wattmeter by carefully and fill them in table 1 Table 1: The measured parameters during open circuit test of the induction motor Measurement Parameter VLL Value 7640 IL 0.48A Pl P2 75 W 75W Pinput 5. Take the readings quickly so that the machine does not heat up due to full load copper lossestaking place at this condition. 6. Reduce the voltage to zero and turn the main switch off. Discussion: 1. Draw the circuit diagram of short circuit test using PSIM. Give some explanations 2. What is the value of the slip? (unity) 3. What happened to rotor's resistance? 4. Is the input voltage small or rated during short circuit test? Why? 5. Calculate the RX,X' Theory: For this test, the motor shaft is blocked by your hand so that it cannot turn. The motor terminals are connected to a 3-phase supply. The rotor becomes the secondary of a transformer operating at the supply frequency. So, the blocked rotor test is similar to the short circuit test on a transformer. It is performed to calculate the series parameters of the induction machine i.e., its leakage impedances. The rotor is blocked to prevent rotation and balanced voltages are applied to the stator terminals where the rated current is achieved. Under the reduced voltage condition and rated current, core loss and magnetizing component ofthe current are quite small percent of the total current, equivalent circuit reduces to the form shown in Fig.(1). R1 + M jX1 m Isc jX2' R2' m Vph Fig. 1: Equivalent circuit for blocked rotor test The slip for the blocked rotor test is unity since the rotor is stationary. The resulting speed-dependent equivalent resistance r2' {(1/s)-1} goes to zero and the resistance of the rotor branch of the equivalent circuitbecomes very small. Thus, the rotor current is much larger than current in the excitation branch of the circuitsuch that the excitation branch can be neglected. Voltage and power are measured at the motor input. Experimental Procedure: 1. Connect the circuit as shown in the connection diagram in Figure 2. 11 U O A V No W 12 A 2 > 0 U₁ IM VLL1 T V Shaft VLL2 W Heavy Mechanical Load Fig.2. Short circuit test of induction motor 2. Before starting, ensure that the shaft is blocked completely from rotating. 3. Increase the voltage to the machine such that it draws rated current.

Power System Analysis and Design (MindTap Course List)

6th Edition

ISBN:9781305632134

Author:J. Duncan Glover, Thomas Overbye, Mulukutla S. Sarma

Publisher:J. Duncan Glover, Thomas Overbye, Mulukutla S. Sarma

Chapter3: Power Transformers

Section: Chapter Questions

Problem 3.28MCQ

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