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f) Oil Oil leakage through the tank cover, bushing / valves etc. if any

A sample of oil should be taken from bottom of the tank and tested for the Electric strength (break down voltage) which should not be below 50 KV (RMS) when tested on a standard test gap as specified in IEC 600296.

UNLOADING

Transformer and all packing cases containing the accessories should be handled in right position indicated, and while handling should not drop down to avoid damages to the delicate instruments packed inside.

a) Lifting : The transformer should be unloaded by means of crane or lifting device of sufficient capacity. (Please refer the rating plate for details of weight). All lifting lugs provided for the purpose must be used for the lifting of transformer to avoid unbalance and undue stresses on the lug. Parts other than lifting lugs should not be used for lifting.

b) Jacking : Four jacking lugs are provided on transformer, each designed to share quarter load. While using jacking pads, utmost care should be exercised in the proper application of jacks, as any improper application will not only damage the jacking pads but also the transformer.

c) Towing : Rollers / wheels should be used for shifting the transformer from one place to other roller axles or radiators should not be slinged for the purpose of towing. Haulage holes provided on the tank should be used.

d) Packing cases : Cases containing various accessories should be handled carefully so that the contents are not damaged.

STORAGE

a) Main transformer : On receipt of the transformer at site, it is desirable to erect and commission with minimum delay.

If the transformer is not required to be commissioned immediately, it should be properly stored on wooden base & case to avoid deterioration of external finish.

Transformer dispatched with dismantled conservator, may absorb moisture when stored for long periods due to entire tanks not filled, with oil, therefore best way to avoid this, is to mount conservator temporarily and fill with oil to filling level mark. Silicagel breather must be fitted in position and checked periodically for the condition of gel to ensure that it remains blue. The gel should be reactivated or replaced once it turns pink. It is advisable to check the condition of gel every week. Oil should be circulated and filtered periodically, to ensure that megger values do not drop. Past experience shows that, if megger values become too low, it is very difficult to improve them. It is desirable to check Electric Strength of oil at least once in a month.

b) Accessories : Accessories like bushings, explosion vent, buchholz relay, dial type temperature indicator, terminal box, magnetic oil gauge etc. should be repacked in packing case and stored indoors till such time they are required. They are likely to get damaged if they are stored outdoors.