Answer to Question #223964 in Electrical Engineering for ZOLEKA

Question

Multiple Choo questions
Question 10
Th goal of the equal area criteria in transient stability is to determine whether a system
is stable or not without having to completely integrate the system response. The
system will be stable after the fault if:
(1) The acceleration area is greater than 1.0 per unit.
(2) The acceleration area is greater than the deceleration area.
(3) The deceleration area is smaller than the acceleration area.
(4) The deceleration area is greater than the acceleration area.

Question 1
Which of the following is an advantage of using bundled conductors in transmission
lines?
(1) They reduce radio interference and corona at the cost of increasing line series
reactance.
(2) They reduce line series reactance, radio interference and corona.
(3) They increase line charging reactance and series reactance.
(4) They have high tensile strength and increase the skin effect.

Answer 1

Question 1

Consider the behavior of a synchronous machine to some impacts due to disturbances.

At the time of occurrence of a fault, the machine will start to accelerate. When the fault is cleared, it will continue to increase speed before it reaches to its peak value (δc).

When deceleration area is greater than the acceleration area, the system will decelerate entirely before getting accelerated again. Due to the fact that the rotor inertia will force the successive acceleration and deceleration areas to become smaller than the initial values. Causing the system to reach steady state.

Question 2

With increase in self inductance per phase will be reduced compared to single conductor line. This results in lesser reactance per phase compared to ordinary single line. Hence lesser loss due to reactance drop.

Bundled conductors per phase reduces the voltage gradient in the vicinity of the line. Thus reduces the possibility of the corona discharge. 

Bundled conductors reduces radio interference due to the dact that magnetic field around it is not intense as solid conductors.

Answer is (2)