Which device helps prevent arching and pitting?

Which device helps prevent arching and pitting?

• A. Resistor
• B. Diode
• C. Inductor
• D. Capacitor

Answer: (D)

Arching and pitting happen when a switch interrupts current in a circuit with inductive energy, causing a rapid voltage spike that can jump the gap and form an arc, damaging the contact surfaces. A capacitor placed across the switch acts as a snubber, absorbing the transient energy and smoothing the voltage as the contacts open. This keeps dv/dt low and clamps the peak voltage, preventing the arc from forming and protecting the contacts from damage. Other components don’t provide the same transient suppression: a resistor alone wastes energy without limiting the spike, a diode mainly blocks reverse current and doesn’t smooth the transient across an AC switch, and an inductor resists changes in current and can actually contribute to larger spikes when the circuit opens. The capacitor is the device that best prevents arching and pitting by damping those switching transients.

Arching and pitting happen when a switch interrupts current in a circuit with inductive energy, causing a rapid voltage spike that can jump the gap and form an arc, damaging the contact surfaces. A capacitor placed across the switch acts as a snubber, absorbing the transient energy and smoothing the voltage as the contacts open. This keeps dv/dt low and clamps the peak voltage, preventing the arc from forming and protecting the contacts from damage.

Other components don’t provide the same transient suppression: a resistor alone wastes energy without limiting the spike, a diode mainly blocks reverse current and doesn’t smooth the transient across an AC switch, and an inductor resists changes in current and can actually contribute to larger spikes when the circuit opens. The capacitor is the device that best prevents arching and pitting by damping those switching transients.