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Wherever transformers are mounted on poles the structure should be strong enough to withstand weight of the transformer, wind pressure and other atmospheric conditions.

Erection of transformer :

Generally small transformers upto 1000 KVA are despatched oil filled fitted with all fittings. Fittings dismantled to facilitate transport, may be reassembled in the following sequence depending on the site conditions.

Sequence of erection :

a) Fitting of rollers

b) Oil check

c) Conservator

d) Buchholz relay and pipe work

e) Silicagel dehydrating

f) Explosion vent

g) Terminals HV LV bushings or cable boxes, CT terminals etc.

h) Topping up of oil

i) Radiators

j) Temperature indicators

k) Marshalling Boxes

Details of erection :

All fittings and accessories should be assembled as shown in outline drawing.

a) Rollers :

i) Before mounting of rollers they should be checked for soundness of casting and that bearing surmace is not damaged.

ii) Bearing surface should be greased or oiled before mounting.

iii) Assembly of rollers become simple if the transformer is lifted by overhead crane or pully block. Transformer may be jacked up with mechanical or hydraulic jacks.(Jacking pads are provided for transformers 1600 KVA and above). Height of jacking pads from ground, without wheels in positions, is not less than 300 mm. Suitable wooden or steel packing may be given under jacks to raise the jack height.

b) Oil check :

A sample of oil should be taken out from bottom of tank and tested for the Electric strength, ( break down voltage ) which should not be below 30 KV (RMS) when tested on a standard test as specified in IEC 600296 Table 1-9. (Electrode dia. 120.5 mm