If the AC mains input to a regulated power supply rises by 5%, what is the approximate impact on the DC output voltage?
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Answer: D. 5%
Explanation
In a simple linear unregulated power supply, changes in input AC mains translate directly to the DC output. A five percent rise in the AC input voltage causes a proportional five percent rise in the DC output voltage. Without active electronic regulation, output voltages fluctuate directly with utility grid variations. Unregulated power supplies typically consist of a transformer, rectifier, and filter capacitor without feedback control. Linear power scaling means output parameters follow input parameters closely based on transformer turns ratios. Grid voltage fluctuations are a common operational challenge in electrical power distribution networks.
Sensitive electronic equipment requires regulated power supplies to isolate internal circuits from grid fluctuations. Unregulated supplies are suitable only for robust loads where exact voltage stability is not strictly required. Power supply designers use regulators to prevent input mains variations from affecting downstream components. Larger percentage changes like ten or twenty percent overestimate the linear response of standard transformers. Zero change would imply perfect regulation, which is impossible in a purely unregulated power supply design. Fixed voltage outputs only occur when active regulation circuitry is present to suppress input variations.
- Subject
- Engineering
- Category
- Electrical Engineering
- Topic
- —
- Difficulty
- medium
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