Third Lesson Induction Motor

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Third Lesson Induction Motor

  1. 1. CLIL experience Content and Language Integrated Learning 3 rd Third lesson
  2. 2. <ul><li>The induction motor consists of a stator and rotor. The stator is connected to the three phase supply & produces a rotating magnetic field. So an induction motor is like a transformer with stator forming primary winding and rotor forming the secondary winding with the small air gap in the magnetic circuit. </li></ul><ul><li>Upon increasing voltage at no load, reactive current drawn by induction motor will increase, therefore power factor of induction motor decreases but total current drawn will increase upon the increased voltage at no load. </li></ul><ul><li>Here power is measured by two wattmeter method . The advantage of using two wattmeter method is, we can also measure power factor along with power consumed. When power factor is equal to 0.5 one wattmeter will show 00 Watt but the second will give some reading. </li></ul>Three-phase induction motor OBJECT: To study the effect of applied voltage on power factor & current drawn by 3-Фinduction motor
  3. 3. Three-phase induction motor <ul><li>For the performance analysis of induction motor, we need to have motor parameters. In those cases where motor parameters are not readily available from the manufacture, they can be approximated from different tests. One of them is no load test . </li></ul><ul><li>Purpose of this test is to find out no load losses i.e core ( magnetizing reactance ) and mechanical losses for at this condition power consumed is basically because of these losses. </li></ul><ul><li>Balanced three phase voltages are applied to the stator terminals at the rated frequency with the rotor uncoupled from any mechanical load. Speed, current, voltage and power are measured at the motor input. </li></ul>OBJECT: To carry out no load test of 3-phase induction motor
  4. 4. Three-phase induction motor CIRCUIT DIAGRAM APPARATUS 1. Voltmeter 2. Ammeter 3. Two wattmeters 4. Auto transformer 5. speed-meter (tachometer) OBJECT: To carry out no load test of 3-phase induction motor Induction motor <ul><li>AIMS </li></ul><ul><li>no load losses </li></ul><ul><ul><li>mechanical losses </li></ul></ul><ul><ul><li>Iron losses </li></ul></ul><ul><ul><li>magnetizing reactance </li></ul></ul><ul><li>no load current </li></ul><ul><li>factor power </li></ul>rpm
  5. 5. Procedure <ul><li>Choose the apparatus and measuring instruments. </li></ul><ul><li>Choose the connection: star or delta </li></ul><ul><li>Make the circuit as shown in figure. </li></ul><ul><li>Disconnect the load connected. </li></ul><ul><li>Start the motor without load at the 10% plus </li></ul><ul><li>of the rated voltage and frequency. </li></ul><ul><li>Note down the readings of all instruments connected. </li></ul><ul><li>Repeat the test with decreasing voltages until </li></ul><ul><li>the motor speed decreases significatly . </li></ul>
  6. 6. Observation - Results
  7. 7. ELABORATIONS
  8. 8. RESULTS <ul><li>Diagram </li></ul>Fig. 2: No-load losses separation diagram.
  9. 9. Separation loss <ul><li>W 0 = losses at no-load </li></ul><ul><li>W F&W = friction and windage losses </li></ul><ul><li>W I = iron losses </li></ul><ul><li>W C = 3RI 2 = stator winding losses </li></ul>c i
  10. 10. Observation - Results
  11. 11. Power Factor 0,29:220 Cosf 0 0,00 0,10 0,20 0,30 0,40 0,50 0,60 0,70 0,80 0,90 1,00 0 25 50 75 100 125 150 175 200 225 250 cosf 0
  12. 12. Separation loss P C P I&S P F&Wo 0 25 50 75 100 125 150 175 200 225 250 275 300 325 350 375 400 0 20 40 60 80 100 120 140 160 180 200 220 240 260 P 0 [watt] P I&S + P F&Wo [watt]
  13. 13. Separation loss V 2 (10 3 ) 0 25 50 75 100 125 150 175 200 225 250 275 300 325 350 375 400 0,0 10,0 20,0 30,0 40,0 50,0 60,0 P 0 [watt] P I&S + P F&Wo [watt]
  14. 14. Answer to the following questions <ul><li>How will the power factor vary if the voltage supply decreases? </li></ul><ul><li>Why is the power measured by two wattmeter method? </li></ul><ul><li>Which wattmeter will show 00 Watt? </li></ul><ul><li>What instrument can the motor speed be measured with? </li></ul><ul><li>How much is the percentage on the current at no load I 0 compared with rated current I N ? </li></ul><ul><li>What is the procedure in order to carry out no load test of 3-phase induction motor? </li></ul>
  15. 15. Translate the following words: <ul><li>Stator core losses ………………………… </li></ul><ul><li>Hysteresis and eddy current ………………………… </li></ul><ul><li>Magnetizing reactance ………………………… </li></ul><ul><li>Power factor ………………………… </li></ul><ul><li>Speed-meter ………………………… </li></ul>
  16. 16. Fill the gaps <ul><li>An induction motor is like a …………….... with stator forming ……..……. and rotor forming the ……………. winding. </li></ul><ul><li>When power factor is smaller than 0.5 one wattmeter (Wb) will show ……………………………………. </li></ul><ul><li>Upon increasing voltage at no load, power factor of induction motor ……………………… </li></ul><ul><li>In those cases where ……………………… are not readily available from the manufacture, they can be carried out from different tests. One of them is ……………………. </li></ul><ul><li>Purpose of no load test is to find out ………………….. i.e. core ……………………….and ……………………. </li></ul>

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