The performance and power flow of three phase induction motor Objective: This test is performed to study the power flow and performance of the three-phase inductionmotor. Theory: for this test, the three-phase induction motor IM is full loaded (full load test), that's when the inputcurrent of the loaded three phase IM equals the rated input current given on its name plate. At the end of the full load test, many parameters which determines the performance of the induction motor is to be calculated. Experimental Procedure: 1- Connect the circuit as per Fig. 1. N 11 A IM > VLL1 > VLL2 A Supply 12 DCGen COUPLING Iload A Load Vload > Nr Tm Pout Meter for measuring IM speed, Fig. 1: Schematic diagram for load test on Three Phase Induction que and output mechnical power Switch-on 3 phase AC mains and start the motor at reduced applied voltage. 2- Increase the applied voltage, till its rated value. 3- Increase the load on the motor gradually using the variable resistive load until the input current ofthe three phase IM equals its rated current given on its name plate. In this case, the full load test is achieved. 4- Record the required readings at full load test in table (1). 5- Reduce the load on the motor and finally unload it completely. 6- Switch-off the supply to stop the motor. P1 P2 VLL Nr Tout Parameters (watt) (watt) (volt) (r.p.m) (mN.m) Measured 64 77.5 242 1351 654 values Calculations: Using tablel, equivalent circuit in figure 1, power flow diagram in figure 2 and the per phase values of resistances and reactance's of the three phase IM that are calculated in the previous tests, find the following parameters in the purpose of studying the performance and the power flow of the three phaseinduction motor: 1. Find the synchronous speed Ns, motor slip S and slip speed ns of the three phase IM given that themotor has four poles fixed at the stator. 2. Find the frequency of the rotor 3. Find the input power factor of the three-phase induction motor 4. Find 11, 10 and 12' using equivalent circuit in Figure 1 (use current divider for 10 and 12'). R1 jX1 R2' ° jX2' m lo lc Im Vph R2*((1-s)/s) Rc jXm Fig.1. Per phase equivalent circuit diagram of induction motor 5. Find stator copper losses Pstator-Cu 6. Find core losses Pcore 7. Find air gap power Pg