Is the dry transformer lightning proof
Lightning protection of dry-type transformers is necessary. It is thought that dry-type transformers are manufactured using the principle of electromagnetic induction. Once the electromagnetic waves and lightning emitted by dry-type transformers are triggered, the dry-type transformers will be in danger of electric shock. It is a practical point to install lightning arresters for dry type transformer lightning protection, so the installation of lightning arresters is essential.
(1) Set the lightning arrester correctly. Over-voltage of forward and reverse conversion waves may appear on the distribution dry-type transformer. In order to prevent the dry-type transformer from being damaged by a lightning strike on the 10kV line, the distribution dry-type transformer of Y / Y0 or Y / Y wiring should be at its high and low voltage. A set of valve type arresters are installed on each side. Practice has proved that the closer the lightning arrester is to the dry-type transformer, the better the lightning protection effect. The high-voltage and low-voltage side arresters can be installed on the side of the top cover of the dry-type transformer, and the dry-type transformer shell, the arrester down conductor and the dry-type transformer neutral wire are connected together, and the three are grounded together. The grounded down conductor should be a copper stranded wire (or steel stranded wire) with a cross-sectional area of 25mm*2, and the length should be short, so that the lightning overvoltage on the dry-type transformer for power distribution is similar to the residual voltage of the arrester. Reduces the risk of breakdown of dry-type transformer insulation.
(2) Regularly test lightning arresters. In order to protect the dry-type transformer from lightning strikes, for 100kVA and earth-distributed dry-type transformers, the lightning arrester should be tested once a year and the grounding resistance should not be greater than 4Ω lightning arresters below 100kVA should be tested every two years. And the grounding resistance value must not be greater than 10Ω; the unqualified should be dealt with in a timely manner.
(3) Test the ground resistance. Every year before the thunderstorm season (February to March), the grounding resistance of the dry-type transformer is tested. If it does not meet the specified values, take timely measures and check the lightning protection facilities. Pay particular attention to the down conductor at the soil junction and all joints. Check to make it meet the requirements. In order to reduce the lateral measurement error and ensure personal safety, the ground resistance value should be measured with the ground down conductor disconnected.