Electrical Engineering Answers

A three-phase, 415 V load takes a line current of 800 A from a 3300/415V delta – star transformer. The 3300V system is supplied from an 11000/3300V star – star transformer. Draw the circuit diagram and, assuming no losses, find both line and phase values of voltages and currents in each part of the circuit. What will be the turns ratios of both transformers?

What is the ground voltage with neutral? Why does it occur? How many Volts should it be? What can be done to prevent and eliminate it?

A salient –pole synchronous generator has the following per-unit parameters; Xd = 1.00, Xq=

0.60, ra= 0.02Ω. If the generator is delivering rated KVA at rated voltage and at 0.8 p.f leading,

compute the power angle and the excitation e.m.f. Draw the phasor diagram also.

A three-phase, 415 V load takes a line current of 800 A from a 3300/415V delta – star transformer. The 3300V system is supplied from an 11000/3300V star – star transformer. Draw the circuit diagram and, assuming no losses, find both line and phase values of voltages and currents in each part of the circuit. What will be the turns ratios of both transformers?

(a) An alternating voltage has the equation v(t) = 222 sin (314t + 70°). What are the values of r.m.s. voltage, average voltage, frequency and the instantaneous voltage when t = 5 ms.

Design a TDM system to handle 3 PAM channels if the maximum input frequency of each channel is 5 kHz.

What are the differences between solid and gas filled cables?

draw the output waveform indicating proper scales on the time and voltage axes for the given input waveform (vi) to the circuit shown resistance 10 ohm,60 ohm, amplifier has voltage-12v and output resistance 10kohm,10kohm

a) The information signal given Vm (t) = 0.20 sin (2 x 10^3 t ) + 0.25 sin (2 x 10^3 t)

is superimposed over the carrier Vc (t) = 10 sin (2π x 100 x 10^6 t) V to give AM modulated wave. Calculate the AM modulation index, bandwidth of AM signal and total power radiated when AM wave is transmitted using half wave dipole antenna.


b) A 2000 Hz modulating signal of the maximum amplitude of 2 V is fed into a FM

generator produces a frequency deviation of 4.25 kHz. What is the modulation index? If

the amplitude of the modulating voltage is kept constant but its frequency is raised to 6

kHz, what is the new frequency deviation (∆f).

A cast steel frame is to be used as the core of an inductor.





An 800 turn coil is wound on the centre limb of the frame which has two similar outer limbs in parallel with each other.


The frame has the following parameters:


Outer limb: c.s.a. of 2000 mm2 and length of 700mm.


Centre limb: c.s.a of 4000 mm2 and length of 250 mm.





Determine the coil current to set up a flux of 1mwb if a saw-tooth (an air-gap) of 1mm is cut in the centre limb.





The relative permeability of steel is 1000.