Arc faults - especially at very high energies - in transformer windings, bushings and tap changers are rare, but when they do occur, they can have catastrophic consequences. Within milliseconds, tremendous heat is generated; the insulating oil vaporizes, and the pressure rises dramatically. Without sufficient countermeasures, the process runs uncontrolled, and the effects can be serious, with potentially devastating consequences for people, the environment and infrastructure.
Maximum protection against electric arcs
If an arc forms in a transformer, this can have devastating consequences for the transformer surroundings. With the BPS - Burst Prevention System - from Maschinenfabrik Reinhausen, grid operators can minimize the damage caused by such an incident.
Maximum protection against electric arcs
If an arc forms in a transformer, this can have devastating consequences for the transformer surroundings. With the BPS - Burst Prevention System - from Maschinenfabrik Reinhausen, grid operators can minimize the damage caused by such an incident.
In order to minimize the risk and reduce pressure in as controlled a manner as possible, designs and protection systems have been and continue to be improved, for example with robust transformer vessels. To complement this, MR has developed the Burst Prevention System (BPS) with intelligent pressure management. This results in a transformer that minimizes the possible effects of such damaging events for operators and industrial companies.
Reinforcements arrive
Reinforcements arrive
The engineers at MR have scrutinized and reinforced all relevant parts on the on-load tap-changer: from the on-load tap-changer cover to the gear unit, screw connections, flow relay and sight glass through to the pressure relief valve for a directional oil drain. Computer simulations show that the BPS can handle malfunctions of up to 10 megajoules in 80 milliseconds and 50 bar pressure. Although most arc flashovers are harmless due to low energies, and the standard protective devices can withstand them, there are also faults with energies of several megajoules. The immense heat generated in such cases causes the surrounding insulating oil to vaporize, and the resulting gas quickly builds up high pressure.
„The total cost of a transformer fire is typically two to three times the cost of a replacement transformer.“
Strong Protection
The reinforcements enable the tap-changer cover to withstand this pressure, and the pressure relief device can then release the oil and pressure in a controlled manner. In rare cases, however, this is not enough, and the pressure becomes so great that it expands the walls of the on-load tap-changer housing. In such cases, the cover continues to hold and the pressure instead breaks open the housing base and escapes into the interior of the transformer. The flexibility of the tank is so great that it absorbs all the energy without oil escaping uncontrollably, and the surrounding area remains unaffected. The functional principle of the BPS was not only validated in numerous simulations, but also in a test with a real arc in which the BPS successfully withstood pressure of around 40 bar caused by a 5.6 megajoule arc within 50 milliseconds.
Why the BPS is a game changer
A transformer fire is not only a safety risk, but also a considerable financial burden. With the BPS system, operators can significantly reduce these risks, especially in critical areas where reliable protection is essential:
- Valuable infrastructure: The BPS prevents expensive consequential damage in substations and industrial plants.
- Sensitive ecosystems: In water protection zones or nature conservation areas, the BPS reduces environmental hazards.
- Offshore wind farms: The BPS minimizes the risk of fire in hard-to-reach facilities.
- Urban safety: The BPS reduces the danger to people in urban areas.
- Transformers in buildings: The BPS protects employees and prevents damage to buildings in industrial plants.
Simulations and real tests with up to 5.6 megajoules of arc energy have proven the effectiveness of the BPS system which can also be retrofitted to existing transformers without costly modifications.
