Engineering Answers

Explain how the presence of shield wires increases the power carrying

capacity of transmission lines.

A 100 MVA, 11 KV, 3-phase generator has a reactance of 20%. The generator

is connected to a 3-phase transformer T I rated 100 MVA, 11/132 KV with 10% reactance. The H.V. side of the transformer is connected to a transmission line of reactance 100 ohm. The far end of the line is connected to a step down three phase transformer T 2 rated 100MVA, 132/11 KV with 10% reactance. The generator supplies two motors connected in parallel on the L.V side of T 2 . The motors are rated at 25 MVA and 50 MVA both at 10 KV with 15% reactance. Taking the generator rating as base;

i) Draw a one-line and reactance diagrams representing the above

power system network showing all the values in per unit.

ii) Calculate the generator terminal voltage.

Explain the rationale for per unit system usage by electrical engineers.

With the help of phasor diagrams, discuss the relationship between the line-to-

line and line to-neutral voltages and currents for both wye and delta connected

systems.

Given a synchronous machine with three separate stator windings a, b, c

displaced physically by 120 o , sketch a graph showing the variations of emfs

developed in the windings against time.

One of the wheels and leaf springs of an automobile, traveling over a rough road, is

shown in Figure 1 below. For simplicity, all the wheels can be assumed to be

identical and the system can be idealized as shown in Figure 2 below. The

automobile has a mass of m1 = 1000 kg and the leaf springs have a total stiffness of

k1 = 400kN/m. The wheels and axles have a mass of m2 =300kg and the tires have

a stiffness of k2= 500kN/m. If the road surface varies sinusoid ally with an

amplitude of Y = 0.1 and a period of l = 6m find the critical velocities of the �

Define hardness. Explain why hard water does not give lather with soap

answer of rod diameter,diameter pf the knuckle pin,, diameter of single eye

Write a report ( 5 or 6 pages).. According to the methodology of Materials Science and Engineering, a tetrahedron showing the relationship between performance, microstructure, chemistry and synthesis and processing of materials, introduce a world-class mechanical product in your country to China.

The design of the gear-and-shaft system depicted necessitates the use of steel shafts of the same

diameter for both AB and CD. It is also necessary that the maximum pressure be 60 MPa, and that

the angle D through which the end D of shaft CD turns not exceed 1.5°. Determine the needed shaft

diameter using G = 77.2 GPa