Which factor does NOT directly affect the surge impedance loading (SIL) of a transmission line?
Answer: C
SIL = V²/Z_c, where Z_c is surge impedance = √(L/C). It depends on L and C per unit length and frequency, but NOT on total line length.
Q.122Medium
What is the significance of 'P-Q capability curve' in generator operation?
Answer: A
The P-Q capability curve defines the operating region of a generator considering thermal limits, stability limits, and excitation limits for both active and reactive power.
Q.123Hard
In a 500 kV transmission line, if the receiving end voltage drops to 0.9 pu, what type of compensation is most critical?
Answer: C
For severe voltage drop (10%), both series compensation (to reduce voltage drop) and shunt compensation (to support receiving end voltage) are typically required.
Q.124Easy
Which type of fault in power system requires the fastest clearance to maintain stability?
Answer: B
Three-phase faults cause maximum current and power imbalance, requiring fastest clearance (typically 100-150 ms) to maintain transient stability.
Q.125Medium
What is the relationship between voltage stability limit and transmission line loading?
Answer: B
As reactive power demand increases with line loading, voltage stability margin decreases. The maximum power that can be transferred is limited by voltage stability.
Advertisement
Q.126Easy
In Indian grid operation, what is the nominal frequency specification?
Answer: C
As per Indian Grid Code 2024 and POSOCO standards, the nominal frequency is 50 Hz with a normal operating range of ±0.10 Hz (49.90-50.10 Hz).
Q.127Medium
Which FACTS device can simultaneously control both voltage and power flow independently?
Answer: C
UPFC has both series and shunt components, allowing independent control of voltage and power flow. It can inject voltage in both magnitude and phase.
Q.128Medium
What does the 'rotor angle' or 'power angle' represent in power system stability analysis?
Answer: A
The rotor angle (δ) is the angle between the generator's rotor magnetic field axis and the reference axis of the network voltage, critical for stability analysis.
Q.129Easy
In a 132 kV system, if the ground fault setting is 200 A, what is the corresponding relay pickup in percentage of line CT primary rating (2000 A)?
Answer: B
Relay pickup percentage = (200 A / 2000 A) × 100 = 10% of CT primary rating.
Q.130Easy
Which of the following correctly represents the relationship in per-unit system for power?
Answer: A
In per-unit system, power is expressed as P(pu) = P(actual)/P_base = P(MW)/S_base(MVA), where S_base is typically the system base MVA.
Q.131Medium
What is the primary function of a Static Synchronous Compensator (STATCOM) in modern power systems?
Answer: B
STATCOM uses power electronics to inject/absorb reactive power independently from active power, providing fast voltage support and damping of oscillations.
Q.132Hard
In transient stability assessment, what does the 'equal area criterion' determine?
Answer: B
Equal area criterion uses the swing equation graph to compare the accelerating area (energy added to rotor) with decelerating area (energy removed), determining stability.
Q.133Medium
Which parameter is most affected by temperature variation in overhead transmission lines?
Answer: B
Temperature causes resistance to change (R = R₀[1 + α(T-T₀)]) and significantly affects sag due to thermal expansion of conductor, impacting clearances and voltage drop.
Q.134Medium
In the latest Indian RE (Renewable Energy) integration guidelines 2024, what is the maximum renewable energy penetration level being targeted by 2030?
Answer: C
India's target for 2030 is 500 GW renewable capacity, aiming for approximately 60% of total electricity generation from renewable sources as per National Action Plan on Climate Change.
Q.135Easy
What is the primary reason for maintaining spinning reserve in power systems?
Answer: B
Spinning reserve (typically 5-10% of peak load) ensures that the system can respond to sudden load increases or unexpected generator tripping without frequency deviation beyond limits.
Q.136Easy
In Indian power systems, what is the standard voltage level for inter-state transmission?
Answer: B
Indian power system uses 220 kV and 400 kV for long-distance inter-state power transmission as per POWERGRID standards.
Q.137Easy
What is the purpose of a surge arrestor in a power system?
Answer: A
Surge arrestors protect equipment by limiting transient overvoltages caused by lightning strikes and switching operations.
Q.138Easy
Which of the following is NOT a function of a circuit breaker in power systems?
Answer: C
Circuit breakers handle fault interruption and normal switching, but voltage regulation is managed by transformers and SVCs, not circuit breakers.
Q.139Medium
In load flow analysis using Newton-Raphson method, what determines the convergence rate?
Answer: B
The convergence rate of Newton-Raphson method is determined by the Jacobian matrix's condition number and the initial guess proximity to solution.
Q.140Medium
What is the primary advantage of using HVDC transmission over HVAC for long distances?
Answer: C
HVDC reduces I²R losses (proportional to current squared) and eliminates reactive power flow, making it ideal for long-distance bulk power transmission.
