Electrical Engineering Answers

A 3 phase, 400 V, 50 Hz, 4 pole, star connected SCIM has the following per phase constants

in ohms referred to stator:

r1= 0.15, x1=0.45, x2=0.45, Xm= 28.5

Rotational losses= 400W.

Compute stator current, rotor speed, output torque and efficiency when the motor is operated at

rated voltage and frequency at 4% slip.

A 10kW, 400 V, 4pole, delta connected SCIM gave the following test results,

N.L. test: 250W, 400V, 8A, B.R. Test : 1350W, 90V, 35A ,

The stator winding resistance/phase is 0.72 ohms/phase. Calculate rotational losses and the

equivalent circuit parameters of the motor.

Some foreign countries, particularly those in the early stages of industrial development, are known to illegally copy product designs and technologies that originated from developed countries. What are the best ways for small businesses to protect their technical knowhow in foreign countries?

A company decides to offer an average annual raise of 8%, although the current inflation rate is 10%. Each engineering manager decides on the best way to distribute the salary increases to his or her staff. However, if everyone gets an increase of 8%, there will be no differentiation between strong and weak performers for the previous year. What should you do as an engineering manager?

a block of iron mass 60kg must be heated from 20 degrees Celsius to 300 degrees Celsius. the specific heat capacity of iron is470J/kg k. the effeciencyof the system is 71%. the available supply voltage is. 230V. the process must be completed within 2 hours. if electricity from eskom is presentlyR1, 77 kilometers per hour. determine the value of current drawn from the source and the total cost of the process

the rod has a diameter of 15mm and 30 cm long. the thickness of the gold layer should be 0.2mm. the electromechanical equivalent of gold is 1.118 mg and density of gold is19300 kg/m^3. if the current process is executed with a current of 130A how long will it take to complete

The metal bar is AB =10mm, DA=18mm, BC =220cm and the resistivity of the metal is 0,012 micro ohms. what is its tip to tip resistance

Design a sequential circuit with two D flip-flops A and B, one input x, and one output y. When x = 0, the state of the circuit remains the same with output y=1. When x = 1, the circuit goes through the state transitions with output y=0. The state transitions from 00 to 01, to 11, to 10, back to 00, and repeats. 

Design a sequence detector by using JK flip-flops. The sequence detector has one input x and one output y.

1101 is detected at the streaming input x the output y is set to high (y=1). Unless the desired sequence is detected, the output y remains low (i.e., y=0). The detector should also be capable of detecting the overlapping sequences (if applicable) received at the input.

a) Draw state flow diagram (optimized)

b) Draw state transition table.

c) Find minimized expressions for inputs of flip-flops and output of the circuit.

The rotor impedance of a three-phase, 50 Hz, 1460 rpm, star-connected ring ASM is (0.1+J1.5) Ω and the stator impedance (0.22+J0.35)Ω . With the rotor at rest, the voltage measured between the rings is 90 V. Wind and friction losses of the motor are 350 W. Accordingly, find the copper losses in the rotor when the motor is running at full load.