RC snubber across an SCR: statement and reason Assertion (A): A snubber circuit consists of an R–C series network connected in parallel with an SCR. Reason (R): The voltage across a capacitor cannot change instantaneously.

Introduction / Context:
SCRs are sensitive to dv/dt. A snubber network (a series R–C connected across the thyristor) is widely used to control voltage transients and limit dv/dt, preventing inadvertent triggering and overstress during switching.

Given Data / Assumptions:

• RC snubber connected across SCR terminals.
• Capacitor has the physical property that its voltage cannot change instantaneously.
• Resistor is included to damp oscillations and dissipate energy.

Concept / Approach:

The capacitor initially behaves as a short circuit to a sudden voltage step, thereby reducing dv/dt across the SCR. The resistor moderates peak currents and prevents sustained ringing. This directly follows from the fundamental property of capacitors and explains the topology of the snubber network.

Step-by-Step Solution:

Verification / Alternative check:

Oscilloscope waveforms with and without snubbers show reduced overshoot and dv/dt. Application notes universally advocate RC snubbers for dv/dt control.

Why Other Options Are Wrong:

Given R states a core capacitor property that directly justifies the design in A; they are not independent facts.

Common Pitfalls:

Confusing snubbers with gate networks; overlooking that snubbers mainly protect against dv/dt and voltage spikes, not conduction failures.

Final Answer:

Both A and R are correct and R is the correct explanation of A