10.6 A 3-phase star-connected Alternator is rated at 11 kV (line). The effective resistance and Synchronous reactance per phase are 2.0 and 20 2 respectively. Calculate the percentage voltage regulation for a load current of 100 A at pf of (i) unity and (ii) 0.8 lag [Ans: (i) 7.85% : (ii) 23.634%]

The step down DC chopper uses DC source voltage V(dc) = 200 V and resistive load impedance of 10 ohm. The duty cycle is 0.4 the voltage drop across the switch may be taken as zero, Calculate :   (a) Average and RMS value of output voltage.  (b) Average and RMS value of output current.

Generate a conclusion on this following statements:  Determine and analyze the voltage regulation characteristics of the alternator with resistive, capacitive, and inductive loading.

v. With reference to an 50 Hz3 phase alternator explain how P,Q,V and F are controlled.

Two alternators A and B operate in parallel and supply a load of 15MW at 0.5 power factor lagging. a) By adjusting steam supply of Alternator A, its power output is adjusted to 6MW and by changing its excitation, its power factor is adjusted to 85% lagging. Find the power factor of Alternator B. b) If steam supply of both machines is left unchanged, but excitation of Alternator B is reduced so that its power factor becomes 85% leading. Find the new power factor of Alternator A.

3.

A three-phase star-connected alternator delivers at rated load a current I = 200 A under a voltage of 5 kV-50 Hz (between phases). The load is inductive of power factor equal to 0.87, the resistance of each stator winding is 0.292 and the speed of the rotor is n = 750 r.p.m. The sum of the constants losses and the stator Joule's losses and the rotor Joule's losses is 55 kW. The no load test, at rated frequency, gave: E-4200 V (between phases) for an excitation current lexc = 40 A. The short-circuit test, for an excitation current lexc = 40 A, gave a short-circuit current in the stator windings Ise =2.5 kA. 1- Calculate the numbers of poles of the alternator. 2- Calculate the synchronous reactance (X). 3- Calculate the electromotive force of the alternator (E) between phases for the same excitation current. 4- Calculate the power absorbed by the alternator (Pa).

Q4 A 11 kV, 500 MVA alternator is connected to a slow C.B. through a bus-bar. Determine the three ratings of the C.B, the average RRRV, and the oscillation frequency knowing that it reaches the peak re-striking voltage with 100 µs time.

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Kindly solve the problem with step by step complete solution. Also, put the given and formula used so that I can understand. Thank you. A 2200V, 60 Hz, three-phase, Y-connected alternator has an effective resistance per phase of 0.5 ohm. A field current of 30A produces a full load current of 200A on short circuit and a line-to-line emf of 1100 V on open circuit. Determine the power angle of the alternator when it delivers full load at .80 lagging pf.