Transformer On The Rural Poles, Rainy Days Will Leakage Of Electricity?
In a mountain village in Hunan, heavy rain in the transformer sudden ear-piercing "hissing" sound, the ground flooded with strange blue light - this is the villager Uncle Li witnessed the leakage of electricity shock. After the test showed that the service 18 years of the transformer casing cracks into the rain, insulation resistance from 5000MΩ plummeted to 3MΩ, leakage current is enough to light up 20 100W bulbs. But another village in the same county, the new transformer in continuous rainstorms unharmed, the secret hidden in layers of protection.
I.The insulation system of the "waterproof war suit"
Modern transformer protection level is comparable to diving equipment. IPX4 waterproofing standards to ensure that tilt 45 ° rainstorms will not invade the equipment, silicone rubber composite casing surface creepage distance of 28mm / kV, is the national standard requirements of 1.6 times. In an extreme test, the new transformer was continuously energized for 72 hours under simulated rainstorm (50mm/h), and the leakage current was always below 0.5mA.
Sealed structure is the ultimate defense of waterproof. The elastic expansion structure of the corrugated tank can withstand temperature changes from -30℃ to 120℃, and the double-layer nitrile rubber gaskets realize millimeter-level sealing precision. When the internal pressure fluctuates due to temperature changes, the color-changing silicone in the breather absorbs 99% of the intruding moisture, ensuring that the insulating oil contains less than 15ppm of water.
II.The triple triggers of the leakage crisis
Insulation aging like a broken umbrella. A testing organization found that 12 years of operation of the transformer casing surface has produced 1.2mm deep cracks, rainy day surface leakage current surge 20 times. More dangerous is the oil paper insulation system damp, when the breakdown voltage of insulating oil from 40kV down to 18kV, the equipment is equivalent to walking on the cliff edge of leakage.
Grounding system failure is the invisible killer. Tests show that some rural transformer grounding resistance is as high as 48Ω, far exceeding the safety standard of 10Ω. This leads to lightning current can not be effectively discharged, after a thunderstorm, the fault current through the wet ground conduction, so that the surrounding water area voltage rises to 70V, the formation of fatal step voltage.
Animal infestation caused an accidental short circuit. A mountainous transformer due to snakes climbed into the triggered phase-to-phase short circuit, the arc melted through the box to form a permanent leakage channel. Statistics show that animal-induced transformer failure accounted for 17% of rural power outages, the proportion rose to 29% during the rainy season.
III.The construction of safety defenses of science and technology code
Intelligent monitoring system as an "electronic sentry". Distributed fiber optic sensors installed at the root of the casing can sense the expansion of cracks at the 0.01mm level; micro-water online monitor in the oil every 15 minutes to update the data, when the water content breaks through the 25ppm automatic alarm. After installing the monitoring system in a pilot county, the leakage accidents dropped by 76%.
New materials to construct a "biological defense". The anti-climbing coating improves the contact resistance of animals by 100 times, and the electric field strength on the surface of composite insulated crossbar is reduced by 40%. After adopting a new type of anti-animal transformer in a forest area, the failure rate of animal damage dropped from 3.2 times per year to zero.
The "last 1cm" of emergency protection. The leakage protector cuts off the faulty circuit within 30ms, and the equipotential connection network controls the contact voltage below 12V. In a flooded area in Jiangxi, this system successfully prevented a group electrocution accident caused by flooding.
The practice of Guangdong Power Grid shows that the failure rate of rural transformers after standardized transformation in continuous rainstorms dropped from 3.5 times/100 units per year to 0.2 times. When we look up at the rain silent transformer, that covered with rain marks under the shell, is seven layers of insulation protection, triple monitoring system and five safety lines woven life network. With the application of graphene anticorrosion coating and self-repairing insulation materials, the future transformer or will realize "the more rain the more safe" magical characteristics. The next time a rainstorm comes, those guarding the iron box on the pole, is using technology to redefine the "fire and water compatible" power legend.