Gap protection method of dry-type transformer
Writer： Hengfeng you electric Time：2023-04-10 views：times
The dry-type transformer is cooled by air convection and is generally used for small capacity transformers such as local lighting and electronic circuits. In the power system, the steam turbine, boiler transformer, ash removal transformer, dust removal transformer and desulfurization transformer are all dry-type transformers with a transformation ratio of 6000V / 400V, which are used for national loads with rated voltage of 380V. The cross flow cooling fan for Xuzhou dry-type transformer is a flow fan with no guide vanes at the air inlet and outlet, which is specially used for the cooling mold of dry-type transformer. There are many gaps in the dry-type transformer. Generally, voltage and current can be transmitted between the gaps. If you are not careful, you will get an electric shock. Therefore, the gap of Xuzhou dry-type transformer should also be protected. Here is the gap protection method of Xuzhou dry-type transformer.
Gap protection is generally composed of two parts of the line and angle rods. One is fixed on the insulation of dry-type transformer to connect the live conductor, and the other is grounded. After gap breakdown, the arc rises and lengthens between the angle rods. When the arc current becomes small, it can extinguish the arc by itself. The disadvantage of gap protection technology is that when the arc current is more than tens of AMPS, it can not extinguish the arc by itself. When lightning overvoltage, Single phase, two-phase or three-phase gap may break through the grounding, resulting in grounding fault, two-phase or three-phase short circuit fault, so that the protection action of line power circuit breaker is opened.
At the initial stage of its development and use, power devices are mostly transmitted through bare conductor overhead lines. Overhead conductors are generally 6 ~ 18m away from the ground, and the insulation of lines or equipment is damaged by lightning overvoltage generated by lightning intrusion wave.
When people artificially create insulation weak points, i.e. gap devices, on the line or equipment, the breakdown voltage of the gap is lower than the lightning impulse insulation level of the line or equipment. Under the normal operating voltage, the gap is in the isolated insulation state. When lightning occurs, the strong overvoltage breaks down the gap, resulting in grounding protection and protecting the insulation of the line or equipment.
