QUESTION 2 [25 MARKSI A shunt de motor rated at 6kW, 120V and 1200 r/min has a magnetization curve as shown in Figure 1.

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Question 2 25 Marksi A Shunt De Motor Rated At 6kw 120v And 1200 R Min Has A Magnetization Curve As Shown In Figure 1 1 (63.18 KiB) Viewed 42 times

QUESTION 2 [25 MARKSI A shunt de motor rated at 6kW, 120V and 1200 r/min has a magnetization curve as shown in Figure 1. The armature resistance is 0.1502 and the field resistance is 2002 with and adjustable field resistance of 0 to 4002. The shunt de motor has rated line current of 50A when supplying rated voltage. (a) Determine the value of the adjustable field resistance so that the shunt dc motor operates at no-load speed of 1200 r/min. 15 marks] (b) How much line current is required to start this shunt de motor at rated terminal voltage and using the same adjustable field resistance from (a)? [4 marks) Assuming no armature reaction and using the same adjustablc field resistance from (a), calculate the full-load speed and induced torque of the shunt de motor. [6 marks] (c) Assuming the shunt de motor has armature reaction which causes flux weakening by 5% at rated line current, calculate the full-load speed of the shunt de motor. 15 marks (d) Compare the effect of armature reaction on the motor's flux and speed as load increases from no-load condition to full-load condition. Use the torque-speed curve to aid your discussion 15 marks] 160 w 140 120 100 Internal Generated Voltage, EA 80 60 40 20 0 0 1 2 3 5 7 Field Current, I Figure 1: Magnetization curve for shunt de motor at speed 1200 r/min