MGVCL Exam Paper (30-07-2021 Shift 3)
The purpose of ____ is to check the ability of the circuit breaker to withstand the overvoltages at power frequency as well as undesired value of voltage during lightning and other discharge phenomenon.
Die-electric test on Circuit breaker: These tests are performed to check power frequency and impulse voltage withstand capacity. Power frequency tests are kept on a new circuit breaker, the test voltage changes with a circuit breaker rated voltage. In impulse tests, impulse voltage of particular value is employed to the breaker.
Bus Type - Known Parameter - Unknown Parameter Load Bus -P, Q - V, phase angle Generator Bus - P, V (magnitude) - Q, Voltage phase angle Slack Bus Voltage - magnitude and phase angle - P, Q
After closing switch, Capacitor is behave as short circuit element, So, I(to) = V/R = 10/5 2 At t = infinite time capacitor is behave as open circuit, I(t) = I(to)e^(-t/Ƭ) Ƭ = time constant of circuit Ƭ = R*C = 200 μF I(t) = 5*e^(-t/(500*10^(-6)) = 5*e^(-5000t) A
Value of power factor is varies from 0 to 1. R→PF = 1 L→PF = 0 lag C→PF = 0 lead R-L→0 lag < PF < 1 R-C→0 lead < PF < 1 R-C-L→depends on value of R, L and C. PF = R/Z
EXAMIANS