Dry type transformers are self-extinguishing and fire resistant as construction materials used in the dry type transformer are aluminum, silica (quartz sand), epoxy resins which are very much flame-retardant and self-extinguishing materials.
Self-extinguishing means
· Prevent the development of fire
· Interrupt or slow down combustion processes by removing any of the fire continuing factors such as -heat, oxygen, fuel, exo-thermic action.
In dry type transformer if the cause of fire is removed then the fire will be ceased by itself by continuously consuming the energy of fire. This is done by the construction materials of dry type transformer which are self-extinguishing and fire resistant itself. These materials are aluminium, silica (quartz sand), epoxy resins etc.
1, Low melting point aluminium
Melting point of Aluminum alloys are between 600 and 660 degrees Celsius. This is why when aluminum is exposed to fire environment it will begin to melt (not burn). Also as temperature passes the melting point it will not increase until the whole melt down is completed.
2. Higher Heat conductivity of Aluminum
Heat conductivity of Aluminum is almost four
times greater than that of iron. Specific heat capacity of Aluminum is similar to iron. Reflectivity to thermal
radiation of
fire is 80 to 90% for aluminum and for iron it is 5 to 25%.
3.High heat dissipation rate of aluminium
With the exposure to fire, aluminum will dissipate large amount of heat quickly and at the same time it will absorb huge amount of thermal energy from the fire. These actions are self-extinguishing in nature.
The resin has fire resistance property with the following nature-
· High resistance to ignition of fire.
· Reduced smoke and fume emission.
· Reduced the rate of flame speed.
· Reduced the heat release.