Why Distribution Transformers Can Burn Out?

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Distribution transformer burnout is a common problem throughout the entire power transmission and distribution system. But it is also worth noting that all these problems do have a cause, which we can find out if we go looking for it. In general, it is mainly shown as such:

1. Three-Phase Load Unbalance and Burning Out

In the power grid, due to 3-phase load imbalance, it results in 3-phase in-phase current, thus creating zero-sequence current on the neutral wire. It will cause zero-sequence magnetic flux to be induced in the transformer winding through the zero-sequence current, generating zero-sequence potential in the transformer winding which shifts the neutral point potential: Phase is over load by high current, so damage the winding insulation, the phase with less current can not get the rated current, it affect the operating of the transformer equipment.

2. Overload Burnout

Overload burnout and damage to rural power distribution equipment happen frequently around the Spring Festival and busy farming time as well as irrigation and drainage. Despite strengthened management, the rate of increase of rural power load is rapid. Especially after the promulgation of policies like the "Home Appliances in Rural Areas," farmers have more desire to purchase home appliances, thus causing an increase in the electricity load.

3. Short-circuit fault, burn damage

Whether it is a single-phase grounding or a phase-to-phase short circuit, the low resistance impedance of the low-voltage winding of the distribution transformer will produce large short-circuit currents. Especially in small scale short circuit fault can reach more than 20 times of the rated current of distribution transformer. And this very strong short circuit, there is a big wave of electromagnetic shock and heat. It destroys the distribution transformer. Short circuit faults are the most harmful to distribution transformer.

Nowadays, short circuit faults mainly occur due to first,external damages. Then like example, there is a big line break here. So, if a large truck hits a utility post, it will cause a short circuit. Another cause is untimely checks and repairs on the distribution transfomer equipment and untimely checks on the low voltage metermetering/metering equipment which cause shorts.

4. Lightning Overvoltage Damage

During thunderstorm season, lightning currents often damage distribution transformers, particularly in places where there is frequent lighting. It has been calculated that lightning damage to distribution transformers accounts for over 30% of all damage to distribution transformers. distribution transformer hit by lightning, the high voltage can reach several times the rated voltage of the transformer is generated in the transformer winding If there is no lighting protection facility or if it does not function well for distribution transformer, then a lighting will strike, causing transformer equipment damage.

 More details you can  click to know What Causes Power Transformers To Spark At Night?

5. Due to Feerroesistance Overvoltage:Transformer Burnout

Transformer equipment insulation breakdown and distribution transformer casing flashover caused by ferroresonance overvoltage. The causes of the problem mostly are： Ferroresonance is also one of the ways to produce overvoltage, firstly, there are many harmonic equipment in the distribution network, such as welding machine, line joint, short circuit discharge, grid voltage fluctuation, etc., which will be generated. Secondly, the insufficient maintenance and cleaning of distribution transformer will contaminate the porcelain case with sludge, oil and dust.