PROFESSIONAL ELECTRICAL ENGINEERING

At time t = 0 the charge on the 50-µF capacitor in an LC circuit is 15 µC and there is no current. If the inductance is 20 mH the maximum current is:

• 12 nA

• 15 μΑ

• 15mA

• 15 A

In the left-hand rule, thumb always represents direction of the ________.

• voltage

• force on conductor

• current

• magnetic field

Three capacitances C₁= 6 µF, C₂ = 7 µF and C3 = 18 µF are connected in series across a 120 v supply. Find the voltage across C2.

• 65.22 v

• 18.26 v

• 46.96 v

• 54.78 v

A balanced delta connected load has impedances Z₁ = Z₂ = Z₃. What is the per phase equivalent impedance in wye?

• Z₁/3

• 3Z₁

• 2Z₁ /3

• Z₁

The net reactance in an RCL circuit is

• XL

• Xc

• XC-XL

• XL-XC

What is the largest rated room air conditioner unit that may he attached to a 20-ampere branch circuit that also serves other receptacles?

• 10

• 12

• 15

• 16

A 60-Hz short transmission line, having R = 0.62 ohms per phase and L = 93.24 mH per phase, supplies a three-phase, wye-connected 100 MW load of 0.90 lagging power factor at 230 kV line-to-line voltage. Determine the voltage regulation of the transmission line?

• 3.75%

• 3.20%

• 3.55%

• 3.42%

One-way communications is called

• Half Duplex

• Full Duplex

• Monocomm

• Simplex

In two-wattmeter method of power measurement, the readings of the two wattmeters were

6,717 watts and 2,658 watts, respectively. Find the power factor.

• 0.90

• 0.70

• 0.60

• 0.80

An ACSR conductor has seven steel strands, it is surrounded by twenty-four aluminum conductors, it is specified as

• 31 ACSR

• 31/7 ACSR

• 7/31 ACSR

• 24/7 ACSR