Govt. Exams
Entrance Exams
As per latest POSOCO guidelines and Indian Grid Code 2024, automatic load shedding initiates at 48.5 Hz frequency threshold to maintain grid stability.
CERC Grid Code 2023 specifies operational standards, frequency bands (±2%), and voltage tolerance (±5-10%) for Indian power system.
Series inductance creates inductive reactance that consumes reactive power, while shunt capacitance generates reactive power.
Apparent power S is the vector sum of P and Q, so S² = P² + Q², and S = P/cos(φ), Q = S × sin(φ).
Transformer tap changers are conventional mechanical devices, whereas SVC, STATCOM, and UPFC are electronic FACTS devices for dynamic power system control.
HVDC transmission has lower I²R losses (lower current for same power) and no skin effect, making it economical for distances >500 km like India's inter-state links.
Corona is a luminous discharge that occurs when the electric field strength at the conductor surface exceeds the breakdown strength of air (~30 kV/cm).
Circuit breakers with overcurrent relays (IDMT or instantaneous) provide selective protection and can be reclosed, unlike fuses.
Power system stability requires maintaining frequency near 50 Hz and voltage within ±5-10% of nominal to ensure safe and reliable operation.
Since inductive reactance X_L = 2πfL and capacitive reactance X_C = 1/(2πfC), increasing frequency increases X_L and decreases X_C.
