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FIRE OF TRANSFORMERS.

Working principle of Transformer:
Tap to view working principle of Transformer (In Hindi)

Transformed works on the principle of Faraday's law of mutual induction, which states that whenever a flux linking to a coil changes, it produces a varying flux in the nearby placed coil similar in characteristics and hence an induced E.M.F. is produced in coil. The magnitude of the E.M.F. depends upon the number of turns of the coil. 

#General constructional features of transformers:-

Transformers have the following general constructional features:-

A) Internal construction

. •Winding coils (primary and                          secondary). 
  •Core for providing path for magnetic         flux linkage. 
  •Buchholz relay. 

B) External construction. 

  •Main housing with cooling tubes. 
  •Conservators.
  •Breathers.

#Hazards in transformers:-

A) Hazards due to cooling media (oil) 

• Failure of conservator. 
  a) Leakage of oil. 
•Failure of breather. 
  a) Entry of moisture. 
  b) Entry of dust above leads to the                 contamination and scaling of oil in           turns changes the dielectric and                 chemical properties of oil. 
•Failure of cooling system. 
•Decrease in level of oil. 

B) Hazard due to electrical faults. 

i)Short circuit
ii) Overloading
iii) Failure of Buchhloz relay. 
iv) Over current due to lightening surges. 

C) General hazards 

i) Bombing during war operation. 
ii) Fire due to maniac persons. 
iii) Arson fires. 

Prevention of transformer fires:-

•Temperature rise of T/F should be continuously monitored. 
•Transformer oil should be kept perservators with expansion chamber and NRV. 
•Provision of circuit breakers on both sides of transformer. 
•Provision of isolation switch on both side of transformer. 

#Protection of transformer fires:-

•Periodical checkup and centrifuging of transformer oil. 
•Dilelectric power and level of transformer oil should be checked regularly. 
•Coil insulation should be checked regularly 
•No air pressure line, oil line and stream line should be allowed to pass through cable tunnels. 
•All cable trenches and tunnels leading to transformer should be provided with fire barriers and filled with sandstone dust etc. 
•Non-combustible material barriers should be provided between two adjacent transformers. 
•Bucchloz relay protecting device should be ensured that it is working. 
•Oil circulation through radial vanes should be monitored. 
•Emulsifier's protection system should be provided. 
•Area must be protected with high velocity water spray drencer system. 

Do's and Dont's for Electrical Fire:-
 
Do's:

1.Use the right size of wall insulation connector for tightening electrical contacts. 
2.Use electric hand gloves and rubber shoes while working on panels if any portion of the panel(including enclosed) is live. 
3.Isolate, discharge and earth the electrical equipment/apparatus before working in them. Also discharge any adjacent conductor if there is a possibility of contact with that. 
4.Place rubber mats in front of electrical panels if medium and high voltage. 
5.Keep a minimum clearance of 3 feet in front of the switchboards and panel. 
6.Ensure that the earthing of the panels and switchboards is in good condition. The value of earth resistance should be such that in case of fault, the protection should operate to isolate the fault. 
7.Replace any electrical contact/terminal with signs of overheating. 
8.Use double insulated flexible cables sufficient in size to carry full load current, with all portable electrical equipment. 
9.Ensure earth wire with all probable equipment. 
10.Use correct size and type of plug GOP wherever a plug socket is provided. 
11.Ensure interlocking for all switches so that the covers cannot be opened without switching them off. 
12.Affix 'Danger' notice on all medium and high volatge panel. 
13.Display instructions for the restoration of persons suffering form electric shock at sub-station and other shift control rooms. 
14.Display the relevant single line circuit diagrams near all distribution boards and panels. 
15.Use the right size of 'connection strike for making wire connections. 
16.Test earth resistance at least once in six months. 
17.Carry out preventive maintenance as per the schedules. Use 24-volt lamps only in confined spaces. 
18.Ensure earthing of neutral by not less than two separate and distinct connections with earth. 
19.Report all accidents. 
20.Medium voltage bare conductors should have a minimum clearance of 19 feet from the ground and 4 feet in the horizontal direction. 

Dont's:

While managing the electrical fire, do not:
1) Work on live line or apparatus. 
2) Replace HRC fuses with wire fuses. 
3) Use portable equipment with defective and damaged cable. 
4) Insert plug top in the society without switching off the supply. 
5) Put a fuse in the neutral conductor. 
6) Allow access to live bare conductors. 
7) Keep the junction boxes in open condition. 
8) Put wire loops in the fuse fittings. 
9) By pass any relay, fuse or any part of the switch. 
10) Make changes in the circuits without authority. 
11) Use a defective test lamp. 
12) Use portable lights without a lamp guard. 
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