Safe DC outlet and arc suppressor
This paper introduces a new solid-state circuit for DC power outlet with arc suppression capability. The principle of operation is to detect the load connection instant (or disconnection) to immediately energize (or de-energize) the outlet. The two poles mechanical assembly is formed by a permanent magnet in the two poles receptacle, a Hall Effect sensor in the jack and a solid estate device to perform the electric connection o dis connection of the electric load.
Power contact arc suppression An investigation into the relative effectiveness of snubbers vs. an engineered electronic power contact arc suppressor
Power contact arc suppression is specific to arcing in contacts that switch currents in excess of one ampere. To facilitate this discussion, a contact arc suppression figure-of-merit is introduced enabling a comparison of arc suppression effectiveness between electronic components and engineered solutions. This “Contact Arc Suppression Factor” (CASF), is the ratio of the arc energy without suppression over the residual arc energy with suppression. A CASF of 1 indicates no effect whereas a CASF of 1000 indicates a 99.9 percent reduction in arc energy. This paper concludes by summarizing the relevant key elements from this investigation that enabled the construction of power contact arc suppressors capable of suppressing arc currents well in the kilo ampere range irrespective of the type of load driven by operating voltages in the kilo volt range.
A transient suppression guide.
When the current flowing through an inductor is interrupted, a transient self-induced voltage is produced. The magnitude of the switching transient is primarily determined by (a) the strength of the magnetic field at the moment of switching, (b) the time rate of decay of the field, and (c) the resistance of the circuit across which the reverse polarity potentials induced by field decay appear. First consider the situation in the absence of a suppression network for a contact or a semiconductor in series with an inductor. For a set of contacts, the air gap of the opening contacts initially has a high resistance and only a minute amount of current flows. This allows the induced potential to reach a value high enough to ionize the air gap between the contacts. Then, the resistance of the air gap drops to a very low value and the instantaneous current flow is very great. The stored energy is then dissipated throughout the electromagnetic spectrum as light, heat, and broad band transients. The heat generated vaporizes some of the contact material. As the circuit continues to be opened across the contact, the contact face becomes pitted, and condensation of metal vapor may form a weld between the contacts. For semiconductor components, resistance is again high until the peak inverse voltage of the unit is exceeded. Leakage current then becomes high and damage results. Arc suppression has three purposes: (1) It protects relay contacts from erosion. (2) It pro-