8b. Explain why galvanic isolation is sometimes required and give a specific example. [2 pts]

 1. Given the 60 Hz, balanced three-phase system shown below, find v (t), (11%)

2. Consider the 60 Hz, 345 KV, completely transposed balanced three phase lines as shown below. The radius of each sub-conductor is 0.9 cm. Find the per phase inductance in H/m and per phase capacitance to neutral in F/m. (11%)

3. Find the radius-and center of the power circle for S = P+ j Q with P as the abscissa (x-axis) and Q as the ordinate (y-axis). (1.1%)

4. A round rotor synchronous generator delivers p = 0.8 (real power) at 0.9 power factor lagging to a bus with voltage of 1.0. Assume that the synchronous reactance of the generator is 0.6 and the armature resistance can be neglected. Find the open-circuit voltage of the synchronous generator. (11%)

5. A 380V, 10HP, four- pole, 60 Hz, Y- connected three phase induction motor has a full-load slip of 3 percent. Find the synchronous speed of this motor and the rotor speed of this motor at the rated load. (11%)

6. A 50 KVA, 2200: 220 V, 60 Hz distribution transformer has a leakage impedance of 0.62 + j 1.02 ohm in the high voltage winding and 0.006 + j 0.01 ohm in the low voltage winding. At rated voltage and frequency, the admittance of the shunt branch accounting for the exciting current is 0.003 - j 0.02 mho when viewed from the low voltage side. Draw the equivalent circuit referred to the high voltage side. (11%)

7a. A sine wave and triangle wave have the same (positive and negative) amplitude. The RMS value is the same for both waveforms. [2 pts]

7b. Average power is equivalent to real power, and RMS power is equivalent to reactive power. [2 pts]

7c. For a periodic waveform, the average valuc will always be the same or lower than the RMS value. [2 pts]

7d. For a periodic waveform, the maximum theoretical value for total harmonic distortion (THD) is 1. [2 pts]

110年 - 110 國立臺灣大學_碩士班招生考試_電機工程研究所乙組:電力工程(含電力系統、電機機械、電力電子)#101255

109年 - 109 國立臺灣大學_碩士班招生考試_電機工程研究所乙組:電力工程(含電力系統、電機機械、電力電子)#105857