Three single-phase transformers are connected in mesh. If one transformer is found faulty and removed, what will be the reduction in rating of the other transformer?
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Solution
= 13.4% of its rating
The gain of the circuit shown below is__________.
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Solution
Calculate the power factor of a load, if the meter constant of meter making 1500 revolution is 350 rev/kW-h, when operating at 230 V and 5 A for 7 h.
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Solution
Which of the following is a correct root locus diagram?
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Solution
Both A and B are correct because the root locus in both the cases starts from pole and ends at zero which is the standard form.
A three-phase, fully controlled thyristor bridge converter is used as line commutated inverter to feed 50 kW power at 420 V DC to a three-phase, 415 V(line), 50 Hz AC mains.Consider de line current to be constant. The rms current in ampere of the thyristor is __________.
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Solution
A single-phase half wave uncontrolled converter circuit is shown in figure. A two winding transformer is used at the input for isolation. Assuming the load current to be constant V = Vm sin wt, the current wave form through diode D2 will be
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Solution
V = V2 sin ωt
In first half cycle, D1 will conduct from 0 to p and D2 will not. So, options (a) and (b) can be eliminated and in option (c), there is some voltage at θ = 0 which is not possible, option(c) can also be eliminated.
An alternator operating at 50 Hz delivers 1.0 pu power to an infinite bus and a 3φ fault occurs which reduces the maximum power transferable to 0.3 pu, whereas the maximum power transferable before fault was 1.7 pu, after fault is 1.2pu. Calculate the critical clearing angle made by the rotor.
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Solution
For the logic circuit shown in figure below,the expression-for Y is
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Solution
For the voltmeter circuit shown in the given figure, the basic D’ Arsonval meter used has full scale current of 1mA and meter resistance (Rm) of 100 Ω. The values of the series resistances R1 and R2 respectively are
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Solution
50 Hz, 13.2 kV, 15 MVA, alternator has X1 = X2= 20%,Xgn= 8% and its neutral is grounded through a reactance of 0.5 Ω. Determine symmetrical rms current in the ground when the double line to ground fault occurs on phase Band C. The generator is operating at a terminal voltage of 13.9 kV before fault takes place.
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Solution