Govt. Exams
Entrance Exams
Three-phase faults cause maximum current and power imbalance, requiring fastest clearance (typically 100-150 ms) to maintain transient stability.
Shunt capacitors supply reactive power locally, improving voltage profile and reducing the burden on generators and transmission lines to supply reactive power.
Circuit breakers carry normal load current and automatically open when fault current exceeds preset relay settings, isolating the faulty section.
Indian power system operates at 50 Hz nominal frequency with allowed frequency variation of ±2% (49-51 Hz) as per grid code standards.
Power factor is defined as cos(φ), the cosine of the phase angle between voltage and current waveforms.
Per unit system uses selected base values for voltage, power, and impedance to normalize calculations across different system parts.
Transformers step up voltage for transmission (reducing current and losses) and step down voltage for distribution to consumers.
For a circuit with m independent loops (meshes), exactly m independent mesh equations are required. Each mesh contributes one independent equation. Therefore, for 3 loops, 3 equations are needed.
Number of independent mesh equations equals the number of independent loops (meshes) in the circuit. For m meshes, we need exactly m independent KVL equations.
This is Euler's formula for planar networks: Number of independent loops (L) = Number of branches (B) - Number of nodes (N) + 1. This is fundamental in mesh analysis.
