When is frequency variation a more likely occurrence?

Question

Options

• AWhen using new UPS technology
• BWhen using older UPS technology
• CWhen a generator is heavily loaded
• DWhen using three-phase power distribution

• A
  8% (3)
• B
  5% (2)
• C
  74% (28)
• D
  13% (5)

Explanation

Frequency variation occurs when the source of electrical power cannot maintain a stable rotational speed, and generators are particularly susceptible to this under heavy load conditions. When a generator is pushed near its capacity, its prime mover (typically a diesel engine) may fluctuate in speed as it struggles to meet demand, directly causing the output frequency to deviate from the standard 60 Hz (or 50 Hz). UPS systems - whether old or new - are specifically designed to regulate and condition power output, making frequency variation far less likely from either type; the age distinction in options A and B is a distractor with no real bearing on frequency stability. Three-phase power distribution in option D describes how power is delivered across phases, not the stability of frequency, so it has no special relationship to frequency variation.

Memory tip: Link generators to frequency variation by remembering that frequency is tied to rotational speed - a heavily loaded generator struggles to spin consistently, and an inconsistent spin means an inconsistent frequency.

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