In 1995, an extensive research program on the energetic transfer phenomenon that occurs within a transformer during a short- circuit was implemented by SERGI and resulted in the development of a Magneto-Thermo-Hydrodynamic model (MTH) [1].

	Article Name:- Development of Magneto-Thermo-Hydrodynamic Model and Design of a transformer , On load Tap Charger and Bushing Oil Cable Box, Explosion and Fire Prevention, IEEE publication, ref. F1tpoa Comments:- We will be pleased to give u this article. Please ask us in our Documentation Request

  SERGI successfully validated the MTH model calculations in collaboration with SCHNEIDER ELECTRIC, France Transfo [2]

	Article Name:- Comparison of the SERGI developed Magneto-Thermo-Hydrodynamic Model results with measurements made on a 160KVA Transformer, IEEE Publication, ref. FfTPob Comments:- We will be pleased to give u this article. Please ask us in our Documentation Request

  and the CEPEL Laboratory by comparison with data from experiments carried out on transformers [6].

	Article Name:- TRANSFORMER EXPLOSION AND FIRE PREVENTION Live Tests on Large Transformers: Analysis and Simulations. ref. Arpivp Comments:- We will be pleased to give u this article. Please ask us in our Documentation Request

  The MTH Model was then upgraded to account for the dynamic pressure wave propagation and its interaction with the tank structure [7].

	Article Name:- Study of the pressure wave propagation and the depressurization Process for an electrical Transformer Subjected to Internal Arcing, ref. Arpiyp Comments:- We will be pleased to give u this article. Please ask us in our Documentation Request

Then, SERGI discovered the following physical phenomena:

1. The insulating fluid loses first its dielectric properties. An electric arc then occurs and almost instantaneously vaporizes a mass of liquid when getting in direct contact with the fluid.
   

2. For a given mass of material, volume in its liquid state is much smaller than that in its gaseous state. Consequently, when the arc vaporizes an amount of liquid oil, the corresponding volume of gas created by vaporization is much higher than the volume of the corresponding mass of liquid. During tests made by the CEPEL laboratory experimental results showed that the first Mega joule transferred to the oil, creates 2.3 m3 (80 ft3) of gas.
   
   This massive gas generation occurs in the first milliseconds of the arc. Therefore, the gas bubble tends to expand in order to stay in pressure equilibrium with its surrounding environment.
   

3. Because of the oil inertia preventing the bubble expansion, the bubble cannot expand fast enough to stay in pressure equilibrium. The gas thus is highly pressurized. The pressure peak experimental amplitudes reached 14 bar (200 psi), absolute during the CEPEL tests.
   

4. The pressure difference leads to the generation of pressure waves that propagate throughout the transformer from the initial arc ignition point.
   

5. The first pressure peak created by the first Mega joule travels inside the oil at the speed of sound, 1200 m/sec (4,000 ft/sec) and interacts with the tank structure.
   
   

6. The interaction between the first pressure peak and the tank structure is a progressive process. Each tank component such as welds or bolts is subjected to the first pressure peak only for a very short time. Then, the integration of all pressure peaks will build the static pressure and the tank elasticity will delay the explosion process. This rupture inertia was more than 57 milliseconds during the CEPEL tests. But, if not depressurized by the TP, the tank cannot withstand much longer the inner overpressure.
   

7. Then, the dynamic pressure peak activates the Depressurization Set in less than 2 milliseconds. A suitable opening is then created in the transformer tank to allow the oil and gas to be evacuated before the inner tank static pressure reaches values that are harmful to the transformer.
   
   

8. As a result the TP efficiently prevents the transformer from exploding.