232 / 2024-06-05 23:03:58

Analysis of Breakdown Mechanisms in Heated Short Air Gaps During Contact Opening in Compact DC Circuit Breakers

DC Circuit Breakers, Arc Re-ignition, Paschen’s Law, Critical Field Theory, Air Breakdown

DC commutative circuit breakers, characterised by

their compact size and rapid commutation capabilities, are

increasingly recognised for their potential in DC circuit interruption.

However, challenges such as arc re-ignition significantly

hinder their scalability. This paper reviews traditional predictive

models for breakdown behaviours, particularly Paschen’s

Law and Critical Field Theory, to explore their adequacy in

explaining the mechanisms behind re-ignition post-commutation.

This research addresses the observed discrepancies between

theoretical predictions and experimental results in compact LC

commutative circuit breakers, particularly in scenarios involving

rapid contact separation and the presence of hot gas in the gap.

It proposes that the Critical Field Theory, due to the remaining

noticeable background ionisation, more accurately describes the

breakdown mechanism during contact opening. The proposed

study integrates detailed modelling of temperature distribution,

electrical phenomena associated with the arc, and airflow effects

within the air gap, supported by experimental validations. The

findings enhance our understanding of the electrical breakdown

dynamics and provide insights into improving the design and

reliability of DC circuit breakers.