DC circuit breaker commutation method A DC circuit breaker must use which commutation principle to interrupt current?

Introduction / Context:
Interrupting DC currents is fundamentally harder than AC because there is no natural current zero to aid arc extinction. Hence DC breakers and DC choppers rely on creating artificial conditions to force current to zero and transfer energy safely to commutation components.

Given Data / Assumptions:

• Pure DC network without naturally occurring current zeros.
• Breaker with auxiliary circuitry (capacitors/inductors/semiconductors).

Concept / Approach:

Natural commutation occurs in line-commutated AC circuits when current crosses zero each half-cycle. In DC systems, a breaker must produce a current zero via an alternative path or counter-voltage; this is called forced commutation. Classic methods include resonant LC circuits, counter-emf injection, or solid-state commutation using power electronics.

Step-by-Step Solution:

Verification / Alternative check:

High-voltage DC breakers (mechanical, hybrid, or solid-state) all implement forced commutation with energy-absorbing and surge-limiting networks.

Why Other Options Are Wrong:

(a) and (d) imply natural commutation suffices, which it does not for DC; (c) is unnecessary—forced is the key mechanism; (e) is incorrect since controlled current zero and energy handling are essential.

Common Pitfalls:

Assuming AC breaker behavior applies to DC without modification; underestimating recovery voltage and transient energy constraints.

Final Answer:

Forced commutation