GATE EE 2025 Set 1 — Question 24

MCQ+1 / -0.33EasyPV, PQ & Slack BusesPer-Unit System & Load FlowPower Systems

Power Systems → Per-Unit System & Load Flow → PV, PQ & Slack Buses

Last updated 5 September 2026

Question

During a power failure, a domestic household uninterruptible power supply (UPS) supplies AC power to a limited number of lights and fans in various rooms. As per a Newton-Raphson load-flow formulation, the UPS would be represented as a

Correct answer (A) Slack bus Solution In a load-flow study, the slack bus (or swing bus) is used as a reference bus where the voltage magnitude and phase angle are specified. In an isolated system, such as a household running on a UPS during a power failure, the UPS acts as the primary source that maintains the system's voltage and frequency. Therefore, it is modeled as a slack bus. Turn this into a strength. Explore AI-powered practice and doubt support with Success Tracker.

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Correct answer (A) Slack bus Solution In a load-flow study, the slack bus (or swing bus) is used as a reference bus where the voltage magnitude and phase angle are specified. In an isolated system, such as a household running on a UPS during a power failure, the UPS acts as the primary source that maintains the system's voltage and frequency. Therefore, it is modeled as a slack bus.

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