What are two causes of impulsive transients? (Choose two.)

Question

Options

• ALightning strikes
• BGenerator switch-over
• CAir conditioner starting up
• DElectrostatic discharge (ESD)

• A
  84% (41)
• B
  2% (1)
• C
  4% (2)
• D
  10% (5)

Explanation

Note: The question asks to "Choose two," so both A (Lightning strikes) and D (Electrostatic discharge) are the correct answers, though only A appears listed above.

Lightning strikes and electrostatic discharge (ESD) are the two textbook causes of impulsive transients - sudden, unidirectional spikes in voltage that rise and fall extremely fast, typically in microseconds. Lightning injects massive energy directly into power or communication lines, producing a sharp voltage spike, while ESD releases stored static charge in a similarly brief, high-amplitude burst. Generator switch-over (B) causes oscillatory transients - damped, back-and-forth waveforms - because the transfer between power sources produces a sinusoidal disturbance rather than a single spike. Air conditioner start-up (C) is also associated with oscillatory transients or voltage sags due to the inrush current of the motor, not an impulsive event.

Memory tip: Impulsive transients come from sudden, single-direction energy releases - think of lightning and a static zap as things that strike once and are gone.

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