OPERATING INSTRUCTIONS AND MAINTENANCE NOTES ON
Contents
1. OPERATING INSTRUCTIONS AND MAINTENANCE NOTES ON LIQUID TRANSFORMERS Ocrev srl Via Oltre Agno 2 36070 Brogliano VI ITALY CONTENTS 1 TRANSPORT 2 LIFTING 3 STORAGE 4 ACCESSORIES 5 INSTALLATION AND START UP 6 MAINTENANCE 7 ANOMALIES Ocrev srl Via Oltre Agno 2 36070 Brogliano VI ITALY 1 TRANSPORT The transformer is prepared by the manufacturer ready for operation except for cases where some components like HV LV cable box cooling elements radiators and oil storage tanks are disassembled to obtain the dimensions suitable for transport The components disassembled for the aforesaid reasons must be reassembled at the installation site by very carefully following the instructions set out by the manufacturer 2 LIFTING Lifting can be done by using the appropriate eyebolts remembering to use long enough cables so that H see Fig 1 is never less than L Always use all the existing rings and not only some of them Short lifting may also be done with hydraulic jacks by applying suitable supporting plates under the crate In some cases a forklift may be used Fig 1 An example of lifting 3 STORAGE If the transformer is not installed after a reasonably short time care must be taken Before applying energy carefully clean the transformer by removing dust and other foreign particles and objects that may have deposited on the bushings or other parts of the cover because of the long storage p2. erally the transformer needs no particular expedients for maintenance However to ensure safe and reliable operation it is best to check periodically the frequency of which depends on the environmental and operation conditions a Check the oil level b Check the oil temperature which must never exceed environmental temperature by 60 C considering an environmental temperature of 40 C c After about a year s operation it 1s advisable to take a sample of oil and make it undergo a dielectric test The sample must be taken from the discharge valve at the bottom of the transformer unless it 1s fitted with a special sampling valve d General cleaning from dust and other dirt that may have collected there paying special attention to the bushings e Check the sealing capacity of the gaskets THE ABOVE MENTIONED OPERATIONS MUST BE CARRIED OUT WITH THE TRANSFORMER CONNECTED TO GROUND AND NOT ENERGISED 7 ANOMALIES ANOMALY CAUSE SOLUTION High noise level Undistributed load Overheating Take the load back to the nominal values Insufficient air circulation Check that the values found under the chapter Installation and Start up Ocrev srl Via Oltre Agno 2 36070 Brogliano VI ITALY
3. eriod Ocrev srl Via Oltre Agno 2 36070 Brogliano VI ITALY 4 ACCESSORIES The transformer is usually fitted with the following accessories bushings placed on the primary side bushings placed on the secondary side bi directional rollers lifting lugs off load tap changer for adjusting the transformer ratio thermometer pockets oil conservator oil level indicator Buchholz relay silicagel breather oil filling hole and plug oil drain valve earthing terminals rating plate only for breathing type Depending on the client s requests the transformer may be fitted with particular accessories each of which supplied with its specific description of operation attached to the accessory itself S INSTALLATION AND START UP If not otherwise requested the characteristics indicated on the rating plate of the transformer refer to installations of up to a maximum height of 1 000 m above sea level For correct thermal dispersal of the leaks due to self consumption of the transformer there must be a minimum distance of 30 cm from the wall between the cooling surfaces and the room walls and 60 cm between one transformer and another if there are more than one The room must be dimensioned to permit air circulation of 4 5 m min for each kW of losses If this condition is not met there would be an anomalous increase in temperature compared to that calculated A n
4. ormal environment may be considered as one where the temperature comes within the following values minimum temperature 25 C average annual temperature 20 C average daily temperature 30 C maximum temperature 40 C Temperatures differing from those indicated will have to be studied to establish the causes Ocrev srl Via Oltre Agno 2 36070 Brogliano VI ITALY 1 After the HV LV cables have been connected carried out by keeping count of the respective phase sequence make sure before applying energy that the tap changer is set to the desired transformer ratio 2 Make sure that the silicagel breather has been mounted according to the following modalities remove the hexagon plug let any oil that has entered into the pipe during transport drip out screw up the silicagel breather be careful not to open the drain plug of the oil conservator 3 Check that the oil level in the oil conservator is set to 20 C 4 For parallel operation with other transformers the transformer must respect the following conditions a It must belong to the same vector group as the transformers to be used in parallel according to the following table Three phase transformer connections b Identical value of Short Circuit Current with only the tolerance foreseen by the Standards of the other transformers meant for parallel connection Ocrev srl Via Oltre Agno 2 36070 Brogliano VI ITALY 6 MAINTENANCE Gen
Download Pdf Manuals
Related Search