1. Impact of sparking: During the melting of materials, sparking often occurs due to impurities, excessive current, and uneven molds. When the high voltage (mold) and the ground (lower plate/aluminum plate) are broken down, a short circuit occurs, and the short-circuit current will burn out the mold, materials, lower plate (aluminum plate), etc. At the same time, due to the increase of current, the load on various high voltage components such as high voltage transformers, rectifiers, vacuum tubes, etc. also increases, making them easy to burn out, shortening their service life, and causing serious material burning and scrapping, wasting costs.
2. Function of spark controller: When ignition occurs, the spark arrester immediately operates to cut off high voltage at a fast speed, thereby ensuring that the above hazards are controlled within a small range.
The principle of spark circuit:
1. Structure of spark tube: Like vacuum tube, spark tube is also composed of three electrodes: filament, grid, and screen. There are four corners at the bottom of the spark tube, with the thicker two being the filament pins, the thinner one being the grid pin, and the other two being the idle pins. The protruding part at the top of the spark tube is the pole (screen pole)
2. Working principle: When the spark tube is working, the filament (AC2.5V) provides free electrons, and a positive high voltage (DC110V or above, 1500-2000V for the 5557 tube) is applied to the screen electrode to accumulate positive charges. By applying a signal voltage (around - DC48V) to the gate, according to the principle of "positive and negative charges attract each other, and negative charges repel each other", cathode electrons tend to flow towards the anode, while the negative voltage of the gate plays a controlling role. At this time, no current is generated between the anode and cathode. The gate voltage is actually a voltage applied between the mold (output) and ground. When the adhesive tape is melted, the negative voltage value continuously decreases and approaches 0V. Even when the mold is pressed against debris or the adhesive tape is melted and breaks through the insulation, the signal voltage is 0V, and the gate loses control ability. The filament of the electronic tube and the screen electrode conduct, forming an anode current, and the spark discharges.