Which can cause a swell or surge to occur in the data center's electrical system?

Question

Options

• AUPS failure
• BCRAC unit startup
• CTransformer failure
• DSudden load reduction

• A
  3% (1)
• B
  5% (2)
• C
  13% (5)
• D
  80% (32)

Explanation

A sudden load reduction causes a swell or surge because when a large electrical load is abruptly removed from the system, the power supply momentarily delivers more voltage than the remaining load requires, producing a transient overvoltage condition. UPS failure (A) is incorrect because it typically results in a loss of power or an undervoltage event, not an overvoltage swell. CRAC unit startup (B) is the opposite scenario: large motors draw heavy inrush current when starting, which sags the voltage rather than raising it. Transformer failure (C) generally leads to power loss or irregular undervoltage, not a surge. Memory tip: picture a water pipe where you suddenly close a downstream valve -- the pressure spikes back toward the source; in the same way, removing load abruptly causes voltage to spike, producing a swell.

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