An acb sequence balanced three-phase y-connected source supplies power to a balanced, three-phase δ-connected load with an impedance of 9+15i ω/ϕ . the source voltage in the b-phase is 220 ∠−50∘v. the line impedance is 1 + 1i ω/ϕ. use the single phase equivalent circuit for the a-phase to find the current in the a-phase of the load.

Vibration monitoring this technique uses the noise or vibration created by mechanical equipment and in seme cases by plant systems to detemine their actual condtion. a)- true b)- false

Tom is having a problem with his washing machine. he notices that the machine vibrates violently at a frequency of 1500 rpm due to an unknown rotating unbalance. the machine is mounted on 4 springs each having a stiffness of 10 kn/m. tom wishes to add an undamped vibration absorber attached by a spring under the machine the machine working frequency ranges between 800 rpm to 2000 rpm and its total mass while loaded is assumed to be 80 kg a) what should be the mass of the absorber added to the machine so that the natural frequency falls outside the working range? b) after a first trial of an absorber using a mass of 35 kg, the amplitude of the oscillation was found to be 10 cm. what is the value of the rotating unbalance? c) using me-3.5 kg.m, find the optimal absorber (by minimizing its mass). what would be the amplitude of the oscillation of the absorber?

Acircular aluminum shaft mounted in a journal is shown. the symmetric clearance gap between the shaft and journal is filled with sae 10w-30 oil at t 30°c. the shaft is caused to turn by the attached mass and cord. develop and solve a differential equation for the angular speed of the shaft as a function of time.