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DC Circuit Breaker Arc-quenching Principle

Dec 24, 2016

DC circuit breaker contacts the DC arc-constant, current greater time constant greater arc was killed off.

DC circuit breaker contacts making and long-term carrying capacity similar to the current performance and General AC circuit breaker, no special requirements. DC circuit breakers and AC breaker breaking current of difference, contact DC circuit breaker when breaking would extinguish the arc, arc characteristics and are measures to extinguish arc profile is as follows:

Circuit breaker when breaking contact, immediate and arc between contacts, not only preventing timely segment circuit, may also make the burning loss of contact, at which point the main problem is loss of electrical contact, which is the same on the AC and DC circuits. To understand the cutting arc of DC circuit breakers, first analyze the process of arc and ARC-quenching ability. When the analysis, contact started when the gap is very small, electric field strength is great, easy to heat and a strong field, metal-free escape of electrons from the cathode toward the anode. This impact the neutral gas molecules in the free electron in an electric field, incentive and make it free, positive ion electron, electrons in a strong electric field under the anode move, also impact other neutral molecules and, therefore, in contact gap produces a large number of positive ions and charged particles electrons. Make the gas electrically conductive type into a hot stream of electrons, which arc.

Electric arc is produced, there is free and free, Liberation was due to produce large amounts of heat energy in the arc, mainly free gas heat, especially when the metal contact surface steam after entering the arc gap, gas heat liberation is more significant, larger current, arc power that larger arc temperature higher more arc free factors. Go free because its free ions and electrons when they met in the space you want to compound, re-form neutral gas molecules, and high density high temperature ion electronic, but also to its density and low temperature diffusion of media around. Its results within the arc gap decreased concentration of ions and free, arc resistance is increased, the arc current, which weakened the free.

To out arc, will inhibit free factors and strengthening to free factors, as will arc pulled into narrow sewing, increased moving touch head and gate tablets Zhijian of distance,, narrowed arc diameter, makes its internal of ion concentration increases, on can strengthening diffusion and cooling role, put arc elongated, or in arc internal set obstacles, is local ion and electronic composite, makes to free role is greater than free role, on can will arc out.