Chapter 7: Q17MCQ (page 464)
Oil can be used as a medium to extinguish the arc in circuit breakers.
(a) True
(b) False
Therefore, the correct option is (a) True
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In the circuit of Figure 7.1, and Determine (a) the rms symmetrical fault current; (b) the rms asymmetrical fault current at the instant the switch closes, assuming maximum dc offset; (c) the rms asymmetrical fault current five cycles after the switch closes, assuming maximum dc offset; and (d) the dc offset as a function of time if the switch closes when the instantaneous source voltage is
Solve Example 7.3 parts (a) and (c) without using the superposition principle. First calculate the internal machine voltages and localid="1656758482853" using the prefault load current. Then determine the subtransient fault, generator, and motor currents directly from Figure 7.4(a). Compare your answers with those of Example 7.3.
The dc-offset component of the three-phase short-circuit current of an unloaded synchronous machine is different in the three phases and its exponential decay is dictated by _______.
For the power system given in Problem 7.12, a three-phase short circuit occurs at bus 2, where the Prefault voltage is. Prefault load current is neglected. Determine the (a) Thรฉvenin equivalent at the fault, (b) subtransient fault current in per unit and in, and (c) contributions to the fault from lines 1โ2, 2โ3, and 2โ4.
Even though the fault current is not symmetrical and not strictly periodic, the rms asymmetrical fault current is computed as the rms ac fault current times an โasymmetry factor,โ which is a function of _____.
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