Electrical Engineering Quiz

Given the following phase currents: Ia = 3.5 + j3.5; Ib = - j3; Ic = -2.6 + j1.5. Determine the negative sequence current for phase A.

• -0.313 - j0.678

• 0.313 + j0.678*

• -0.313 + j0.678

• 0.313 - j.0.678

Heating value of coal largely depends on

• Moisture content

• Ash content*

• Volatile matter

• Size of coal particles

Which of the following will take least time in starting from cold condition to full load operation? (Note: Twice lumabas)

• Gas turbine plant

• Hydro-electric power plant*

• Nuclear power plant

• Thermal power plant

Which of the following cannot have a single unit of 100 MW?

• Diesel power plant*

• Hydro power plant

• Steam power plant

• Nuclear power plant

A 69kV three-phase transposed line is composed of one ACSR 336, 400 cmil, 26/7 linnet conductor per phase with a horizontal configuration of D12 = 5 ft, D23 = 5 ft, and D13 = 10 ft. The conductors have a diameter of 0.72 inch and a GMR of 0.0243 ft. Find the inductance per phase per kilometer of the line.

• 1.0963 mH/km

• 1.1116 mH/km*

• 1.1505 mH/km

• 1.1233 mH/km

A series circuit consists of three resistors R1, R2, and R3 which are connected to a 240-V source. If the voltage drop across R1 is 60-V when the current is 4A and R2 = 1.5R3, what is the ohmic resistance R3?

• 15

• 18*

• 27

• 28

A load consists of a resistance R in parallel with a capacitor of reactance X. The load is fed from a single phase supply through a line of impedance 8.4 + j11.2 ohms. The rms voltage at the load terminal is 1200 at 0 degrees V rms, and the load is taking 30 kVA at 0.8 power factor leading. Find the supply voltage.

• 1.2 + j0.35 kV*

• 1.2 - j0.35 kV

• 1.536 - j0.098 kV

• 1.536 + j0.098 kV

A load consists of a resistance R in parallel with a capacitor of reactance X. The load is fed from a single phase supply through a line of impedance 8.4 + j11.2 ohms. The rms voltage at the load terminal is 1200 at 0 degrees V rms, and the load is taking 30 kVA at 0.8 power factor leading. Find the values of R and X.

• R = 60 Ω ; X = 90 Ω

• R = 60 Ω ; X = 80 Ω*

• R = 90 Ω ; X = 60 Ω

• R = 80 Ω ; X = 60 Ω

A three-phase, 345kV transmission line has a series impedance of (4.0 + j60.0) Ω and a shunt admittance of j2.0 x 10-3 S. Using 100 MVA and the line voltage as base values, calculate the per-unit shunt admittance of the line.

• j4.76 pu

• j2.38 pu*

• j3.57 pu

• j5.95 pu

A generator delivers a load through a pair of wires, each of which has a resistance of 0.06 Ω. If the load voltage and power are respectively, 120 volts and 4.8 kW, calculate the power loss in the line wires.

• 96 W

• 198 W

• 192 W*

• 99 W