Instrument Transformers

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Yearly Maintenance :

60-A-01 Y	* Clean the porcelain for dust etc. and check for any chipping.
60-A-02 Y	* Check the Tightness of clamps for jumpers and tightness of nut bolts of supporting structure and terminal bushings.
60-A-03 Y	* Check the foundation for any crack etc.
60-A-04 Y	* In case of hermatically sealed C.T./P.T. there is no necessity for extraction of sample of oil for analysis or for re-conditioning of oil. However oil level has to be checked periodically. Any abnormal change in the oil level indicates leak and should be investigated and attended immediately check the diaphram of pressure felief vent for bursting.
60-A-05 Y	* In case the transformer is not hermatically sealed then check the dielectric strength of oil and record the result. It dielectric strength is poor then recondition/replace the oil.
60-A-06 Y	* Check the secondary terminal connections of the transformer and connection in the junction box for tightness. When the current is flowing in the primary, secondary circuit of C.T. should never be open as this may cause overheating of core and breakdown of the insulation due to the high voltage developed across the secondary terminals.
60-A-07 Y	* Check the tightness of corona ring, if provided.
60-A-08 Y	* Check equipment earthing and see that both the earthings are tight and intact.
60-A-09 Y	* Check the arcing horn gaps if provided.
60-A-10 Y	* Clean the glass indicator with CC L4 and carefully fit the top cover and reseal.
60-A-11 Y	* Measure IR value between primary and secondary primary and Earth.
60-A-12 Y	* Check earthing of earthed end of primary winding of transformers.
60-A-13 Y	* Check pressure of Nitrogen and fill up if necessary.
60-A-14 Y	* After every 8 years all CTs with rubber bellows may be checked for the condition of rubber bellows. as the life of rubber bellows in stated to be 10 to 15 years only. If maybe replaced if necessary.