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GATE 2019: Electrical Machines Quiz 8 (App update required to attempt this test)
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Question 1
A 230V, 20 hp, 60 Hz, 6-pole, 3-phase induction motor driving a constant torque load at rated frequency, rated voltage and rated horse-power, has a speed of 1175 rpm and an efficiency of 92.1%. Determine the new operating speed if a system disturbance causes 10% drop in voltage and 6% drop in frequency. Assume that friction, windage and stray power losses remain constant.
Question 2
A non-salient pole synchronous generator having synchronous reactance of 0.8 pu is supplying 1 pu power to a unity power factor load at a terminal voltage of 1.1 pu. Neglecting the armature resistance, the angle of the voltage behind the synchronous reactance with respect to the angle of the terminal voltage in degrees is ________.
Question 3
A single phase two winding transformer shown below in (fig-1) is reconnected as an autotransformer shown in (fig-2.) If the connection of 200V winding are reversed as shown in (fig-3.) What is value of V1 required to be applied across terminal X2 and H2 to obtain the same 800V output?
Question 4
The per phase equivalent of a synchronous generator feeding a synchronous motor through a transmission line is shown in figure below.
Each machine is rated 10 KVA,400 V 50 Hz. The motor is driving a load of 8 kW. The field current of the two machines are so adjusted that the motor terminal voltage is 400 V and its pf.is 0.8 leading. Determine the magnitude of Eg and Em.
Each machine is rated 10 KVA,400 V 50 Hz. The motor is driving a load of 8 kW. The field current of the two machines are so adjusted that the motor terminal voltage is 400 V and its pf.is 0.8 leading. Determine the magnitude of Eg and Em.
Question 5
The steam input in to a turbo generator connected to infinite bus is increased. Which of the events will take place?
Question 6
The incremental cost characteristics of two generators delivering 200 MW are as follows
For economic operation, the generations P1 and P2 should be
For economic operation, the generations P1 and P2 should be
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Jun 18ESE & GATE EE