Transformer Clearance (Indoor and Outdoor) and Fire Protection-PART-1

TRANSFORMER CLEARANCE (INDOOR AND OUTDOOR) AND FIRE PROTECTION-PART-1

IEC 61936-1-TABLE 3 – GUIDE VALUES FOR OUTDOOR TRANSFORMER CLEARANCES

Transformer type Liquid volume Clearance to other transformers or non-combustible building surface Clearance to combustible building surface Oil insulated transformers (O) 1000 Liter to 2000 Liter 3 Meter 7.6 Meter 2000 Litre to 20000 Litre 5 Meter 10 Meter 20000 Litre to 45000 Litre 10 Meter 20 Meter More than 45000 Liter 15.2 Meter 30.5 Meter Less flammable liquid insulated transformers (K) without enhanced protection 1000 Liter to 3800 Liter 1.5 Meter 7.6 Meter More than 3800 Liter 4.6 Meter 15.2 Meter Less flammable liquid insulated transformers (K) with enhanced protection Clearance to building surface or adjacent transformers Horizonal =0.9 Meter Vertical=1.5 Meter Dry-type transformers (A) Fire behavior’s class Clearance G to building surface or adjacent transformers Horizonal vertical F0 1.5 Meter 3 Meter F1/F2 NILL NILL Note: If automatically activated fire extinguishing equipment is installed, the clearance can be reduced Note: If it is not possible to allow for adequate clearance as indicated in table 3, fire-resistant separating walls with the following dimensions shall be provided: Between transformers (see figure) separating walls. For example EI 60 in accordance (i) Height: top of the expansion chamber (if any), otherwise the top of the transformer tank; (ii) Length: width or length of the sump (in the case of a dry-type transformer, the width or length of the transformer, depending upon the direction of the transformer); Note: Where transformers with a liquid volume below 1000 Litre are installed near combustible walls, special fire precautions may be necessary depending on the nature and the use of the building

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IEC 61936-1-TABLE 4 – MINIMUM REQUIREMENTS FOR THE INSTALLATION OF INDOOR TRANSFORMERS

Transformer type Liquid volume Safeguard Oil insulated transformers (O) <=1000 Liter EI 60 respectively REI 60 More than 1000 Liter EI 90 respectively REI 90 or EI 60 respectively REI 60 and automatic sprinkler protection Less flammable liquid insulated transformers (K) without enhanced protection EI 60 respectively REI 60 or automatic sprinkler protection Less flammable liquid insulated transformers (K) with enhanced protection <= 10 MVA and Um <= 38 kV EI 60 respectively REI 60 or separation distances 1.5 Meter horizontally and 3.0 Meter vertically Dry-type transformers (A) Fire behavior’s class F0 EI 60 respectively REI 60 or separation distances 0.9 Meter horizontally and 1.5 Meter vertically F1/F2 Non-combustible walls Note: Between transformers and buildings separating walls shall be provided. For example EI 60; if additional fire separating wall is not provided, fire rating of the building wall should be increased, for example REI 90

IS 3034: 1993

SIZE OF TRANSFORMER FIRE PROTECTION <=10 MVA or Oil filled Transformers with oil capacity of <=2 000 Liters No fixed fire protection equipment (such as high velocity spray) is required >10 MVA or Oil filled Transformers with oil capacity of >2 000 Litres High velocity water spray system, shall be provided. This system shall be separately mounted and designed to take into account the possibility of a transformer explosion. The water spray deluge valve house shall be located outside the transformer fire zones and protected from radiant heat and other fire effects. The actuation of this system shall be automatic but manual operating valves shall also be provided The positioning of the nozzles should be such to protect all surfaces of the transformer and to give discharge rate for the system not less than 10 Ipm/m of the area to be protected. The automatic high velocity water spray shall be of pre-active with quartzoid bulbs. Distance between two transformers is less than 15 Meter apart or where the oil capacity > 2000 Liters Fire barriers walls shall be provided between transformers. Transformers having an aggregate oil capacity exceeding 2000 liters but an individual oil capacity of fewer than 5000 liters Separating walls shall not be necessary. If the distance between transformers and other apparatus is more than 6 Meter If the transformers are protected by an approved high-velocity water spray system

IS 3034: 1993-TABLE 1 CLEARANCE FROM WATER SPRAY EQUIPMENT TO LIVE UN ATTENDED ELECTRICAL COMPONENTS

Nominal Line Voltage Design BIL Minimum Clearance up to 15KV 110KV 178MM 23KV 150KV 254MM 34.5KV 200KV 330MM 46KV 250KV 432MM 69KV 350KV 635MM 115KV 550KV 940MM 138KV 650KV 1118MM 161KV 750KV 1321MM 196 TO 230KV 900-1050KV 1600-1930MM 287 TO 380KV 1175-1550KV 2210-3048MM 500KV 1675-1880KV 3327-3607MM 500 TO 700KV 1925 -2300KV 3886-4674MM

SECTION 64 IN THE INDIAN ELECTRICITY RULES, 1956

2000 liters of oil installed, whether indoor or out-doors The baffle walls of 4-hour fire rating shall be provided be…