Three Phase Induction Motor Experiment

1 Done by Assist. Ahmad AL Ahmad Three Phase Induction Motor EXPERIMENTS Outline 1. Experiment 1: Introduction to Three Phase Induction Motor 2. Experiment 2: Applying DC test on Three Phase Induction Motor 3. Experiment 3: Applying open circuit test on Three Phase Induction Motor 4. Experiment 4: Applying short circuit (blocked rotor) test on Three Phase Induction Motor 5. Experiment 5: Applying load test on Three Phase Induction Motor 6. Experiment 6: Performance and power flow of Three Phase Induction Motor Instructions: - By the end of each Experiment , report should be submitted individually by each student to the lab s instructor - The experiments require at least Three sessions of 2 hours each to be completed Designed byAssist.

2 Ahmad AL AhmadEMUT itleInductionMotorDone by Assist. Ahmad AL Ahmad Experiment (1) Introduction to Three - Phase Induction Motor 1) What are the input and output of Electric Motors? Different types of Electric motors 2) Check the construction of the Three Phase Induction Motor in your lab. Write a paragraph about the construction and principle work of Induction Motor according to the given process and illustrations in Figure 2. R110kL1100mHM1 RajXsEIaVaL2100mHR210kR310kVf+-RfLfIfArm ature CircuitField Circuit+-MM1M3DC MotorSingle Phase motorThree Phase motorElectric Mechanical Done by Assist.

3 Ahmad AL Ahmad Done by Assist. Ahmad AL Ahmad Done by Assist. Ahmad AL Ahmad Construction and theory of operation of Three Phase Induction Motor . 3) Define the 4 parameters given on the name plate of Three Phase Induction Motor and fill them in table 1. Three Phase Induction Motor name plate Table 1: parameter of name plate of Three Phase Induction Motor PN UN nN IN 4) What is the relation between angular speed, Torque and ouput mechanical power.

4 5) Find rated torque of the Three Phase Induction Motor 6) According to the equivalent circuit diagram of Three Phase Induction Motor given in (a) and (b). Study the equivalent circuit and Define every parameter in table 2. Done by Assist. Ahmad AL Ahmad (a) (b) Equivalent circuit diagram of Three Phase Induction Motor Table 2: The components of equivalent circuit diagram of the Three Phase Induction Motor Parameters and values Definitions V1 E1 E2 Is I2 I 2 I0 R1 R2 RC X1 X2 X 2 Xm s Done by Assist.

5 Ahmad AL Ahmad 7. Connect the armature circuit of the asynchronous Motor to the Three Phase supply. What do you notice? 8. Is Induction Motor a self-starter? Why? 9. Why is it called asynchronous Motor ? 10. What is the relation between synchronous speed, frequency, and number of poles? 11. What is the relation between synchronous speed, Motor speed and Motor slip? 12. Calculate the value of the slip at full load 13. Are asynchronous motors more applicable than synchronous motors? If yes, Why? 14. Compare the equivalent circuit of asynchronous Motor to that of the transformer 15.

6 Give another name for the Induction Motor 16. What are the required Devices in your lab to test the Three Phase Induction Motor Required devices for testing Three Phase Induction Motor TAVIMABS peedTorqueMechanical LoadResistive LoadAmmeterVoltmeterDisplayThree Phase AC SupplyDC SupplyDC GeneratorFieldArmatureELfShaftUVWDone by Assist. Ahmad AL Ahmad Experiment (2) Stator Resistance Test of Three - Phase Induction Motor (DC Test of 3- Phase IM) Objective: To measure the value of the stator resistance of 3- Phase IM. Theory: Basically, a DC voltage is applied to the stator windings of a 3- Phase IM.

7 Because the current is DC, there is no induced voltage in the rotor circuit and no resulting rotor current. Also, the reactance of the Motor is zero at direct current. Therefore, the only quantity limiting current now in the Motor is the stator resistance, and that resistance can be determined. The basic circuit for the DC test is shown in Figure 1. This figure shows a DC power supply connected to two of the Three terminals of a -connected 3- Phase IM. The measured value of resistance of 3- Phase IM should be multiplied by a factor (Skin effect) ranging from ( ) in order to convert its value from DC value to AC value.

8 The skin effect factor depend on the temperature of Motor before test ( ) and the temperature of Motor at the moment of DC test ( ). = + + K= for copper. Procedure: 1- Connect the circuit shown in the Figure below. DC Resistance Test 2- Switch on the DC supply after checking connection by concerned teacher. 3- Increase the supply input voltage slowly from 5V to 40V with step equal to 5V. 4- Record the readings of the measurements in table (1). Done by Assist. Ahmad AL Ahmad Table (1): reading of DC test of 3- Phase IM Vdc (v) Idc (A) 5 10 15 20 25 30 35 40 Calculations: After applying DC voltage to the terminals of the stator winding and taking the reading of the voltage and the current, the relationship between them should be plotted, then the DC resistance can be determined as follows.

9 212111232dcdcdcdcdcdcdcVVVRIIIRR perphase for Y connectionRRperphase forconnection Skin effect = or 1,1,ACDCRRSkin effect where1,ACRis the AC value of the stator resistance per Phase of Three Phase Induction Motor Report: 1- Calculate the stator resistance1,ACRaccording to the above equations. Done by Assist. Ahmad AL Ahmad Experiment (3) No load Test of Three - Phase Induction Motor Theory: The no load test is similar to the open circuit test on a transformer. It is performed to obtain the magnetizing branch parameters (shunt parameters) in the Induction machine equivalent circuit.

10 In this test, the Motor is allowed to run with no-load at the rated voltage of rated frequency across its terminals. Machine will rotate at almost synchronous speed, which makes slip nearly equal to zero. This causes the equivalent rotor impedance to be very large (theoretically infinite neglecting the frictional and rotational losses). Therefore, the rotor equivalent impedance can be considered to be an open circuit which reduces the equivalent circuit diagram of the Induction machine Fig. 1 (a) to the circuit as shown in Fig.