SERGI - System 2000

Fire extinguishing system Type 2000

The nitrogen fire extinguishing system "Drain and Stir" was developed in 1955 by "Electricité de France" and SERGI. In the following 40 years, SERGI sold approximately 3000 systems world-wide for all types of transformers from 5 to 2,500 MVA.

Despite such important advantages as the ease of operation and maintenance and the efficiency of transformer tank fire extinguishing, SERGI 2000 system does not prevent the explosion of the transformer. Thus, it does not allow to avoid the damage caused by the explosion and does not stop the fire of oil spilled around the transformer.

Nowadays, SERGI customers have switched to the TRANSFORMER PROTECTOR, latest Transformer Explosion and Fire Prevention system developed by SERGI. The "Drain and Stir" principle is used in this new equipment as a back-up.




		1 - Isolation Valve 6 - Nitrogen Injection Pipe 2 - Drain Pipe 7 - Fire Detectors 3 - Cabinet 8 - Conservator Shutter 4 - Oil Drain Valve 9 - Buchholz 5 - Nitrogen Cylinder 10 - To Remote Oil Storage Sump


	Differences with TRANSFORMER PROTECTOR

The extinguishing "Drain and Stir" system only acts as a fire fighting device like "Water Spray" systems, which operate once the tank has ruptured and the fire has ignited.

"Drain and Stir" principle is now obsolete as the TRANSFORMER PROTECTOR reacts to internal pressure, before explosion and consequently prevents fire.
Therefore, when transformers explode the tank can not be repaired. Financial losses for customers are very heavy as the transformer and nearby equipment must be replaced.
In addition, the losses caused by electricity production interruption, required for transformer replacement, have to be taken into account.


	Principles


	When transformer explodes, the self-flammable gases start a fire. The energy from the fire heats the surface oil and generates more flammable gases, which maintain and extend fire. Any one SERGI Fire Detector, in addition to the Buchholz signal initiates the "Drain and Stir" sequence.




		Immediately the Oil Drain Valve opens to prevent burning oil from overflowing during nitrogen injection. As soon as drain starts, the flow in the piping between conservator and transformer tank mechanically closes the Conservator Shutter.

20 seconds after start-up, nitrogen is injected at the bottom of the transformer tank.

This action allows to quickly mix the surface oil, warmed by the fire to combustion temperature, with the rest of relatively cold (operating temperature) transformer oil. Therefore, the fire is extinguished within a few minutes.

Nitrogen is injected for 45 minutes to prevent further combustion and ensure oil cooling.