Engineering Answers

A three phase induction motor is wound for 4 poles and is supplied from 50 Hz system. Calculate the rotor frequency when the rotor runs at 600 r.p.m. 

The stator of a three phase induction motor operates from a supply whose frequency is 50 Hz. Calculate the number of stator poles and total number of slots 1n the stator.

A 12 pole, 3-phase alternator drives at a speed of 500 r.p.m supplies power to an 8 pole, three-phase induction motor. If the slip of the motor at full load speed is 4 %, calculate the full load of the motor. 

A 12 pole, 3-phase alternator drives at a speed of 500 r.p.m supplies power to an 8 pole, three-phase induction motor. If the slip of the motor at full load speed is 4 %, calculate the full load of the motor. 

A 1.5 MVA ,3.3 kV, 40 pole, three-phase star connected asynchronous alternator has reactance of Xd = 4.01Ω/phase and Xq = 2.88Ω/phase.For a lagging power factor of 0.8 when delivering full load. Calculate a developed power: 

A circuit of 500 V for single-phase asynchronous motor has synchronous impedance of 3.2 Ω. The armature resistance is 0.3 Ω. Determine the induced emf if the machine develops 31.3 kW and the mechanical losses equals 4 kW

A synchronous motor has an equivalent armature reactance of 3.3 Ω.The field current is adjusted so that the induced emf is 950V. If the motor is taking 80 Kw from the supply at 800V, determine the power factor at which the machine operates. 

A rigid bar, pinned at O, is supported by two identical springs as shown in Fig. Each spring consists of 21

turns of 3⁄4-in-diameter wire having a mean diameter of 6.5 in. Determine the maximum load W that may

be supported if the shearing stress in the springs is limited to 21 ksi.

The bent steel bar shown in figure is 201mm square. Determine the normal stresses at A and B.

A helical spring is provided with a rigid plate at each end. A bolt passes through the spring and the end plates. By turning the nut, the spring is compressed until the coils touch. The height of the unloaded spring is 700 mm, its mean coil diameter is 200 mm, and the diameter of the spring wire is 30 mm. The spring has 20 coils. If the diameter of the bolt is 26 mm and each plate is 26 mm thick. Calculate: a. The elongation of the bolt when the spring is fully compressed b. The stress in the spring wire. (E=200 GPa and G= 80 GPa)