Pre activity before installation of new transformer in the place of old transformer

Installation of new transformer 2.5 MVA 6.6/0.433 KV in the palce of old transformer Some times it becmomes requirement to replace the electrical equipment. It is more dificult when the rating is same but make model is different. I f we do some homework before exection of the job, it saves lot. Simalr case happens when a transformer was having the tan delat high and it was need to replace. A detailed pre-activity review has been carried out before installation on the existing foundation. The observations and required modifications are as follows: 1. Transformer Foundation: Existing foundation size is 40 × 40, while the new transformer base is approximately 41 × 37. The existing concrete foundation size of 59 × 59 is sufficient and will accommodate the new transformer. 2. Radiator Clearance: Existing radiator height is approximately 35, whereas the new radiator length is 45.5. Adequate space is available around the transformer for movement and maintenance. 3. Top Terminal Box (TB) Height: Existing height up to the top TB flange is 69, while the new transformer requires approximately 74. This is the only significant physical modification identified. The existing 30 × 12 dropper will require modification/cutting by approximately 5. A new 43 × 15.5 flange plate, with a 30 × 12 window, will be fabricated and welded suitably to match the new transformer terminal arrangement. 4. Phase Orientation: Existing phase orientation is RYBN, whereas the new transformer is NRYB. Accordingly, the phase sequence will be corrected at the HT-end termination. The neutral connection will be provided through a suitable copper cable loop connection. 5. Terminal Spacing: Existing terminal spacing is approximately 4-7-7-7-5, while the new transformer terminal spacing is 4-10-10-10-6. This minor variation can be accommodated by using suitable copper flexible jumpers, which are available from the recently replaced sand-switch bus duct. 6. Protection and Relay Settings: The existing protection scheme and relay settings will be reviewed and suitably modified as per the new 2.5 MVA transformer capacity and technical parameters before commissioning. Overall Assessment Based on the pre-installation; dimensional and technical review, no major concern has been identified for replacement of TR-176 with the new 2.5 MVA transformer. The required foundation, radiator clearance, terminal spacing, and connection arrangements are manageable with minor modifications. The main activity requiring attention during installation is the top TB/dropper modification and HT phase-sequence correction. Overall, the replacement has been adequately pre-planned and reviewed, and the actual site installation will be closely monitored to identify and resolve any unforeseen hindrance during erection, termination and commissioning.