SR-47898 - The core sheets of the magnetic circuit of transformers exceeding 16 MVA shall be bonded to the core clamping structure through at least one removable core-insulation test link. The link shall be placed in an accessible position. With the bond removed, the core sheets of the magnetic circuit shall be insulated from the core clamping and all structural parts.2.6 Noise SR-47900 - If not otherwise is specified in the datasheet at then the sound pressure level when the transformer is energised, plus when cooling equipment and any oil-circulating pumps are in service, shall not exceed 85 dB(A) at 1m distance measured according to IEC 60076-10 or IEEE C57.12.90 and IEEE C57.12.91 respectively.2.10 Surface treatment SR-47914 - Surface and protective coating for transformers located outdoor in natural ventilated area shall be according to TR0042 cl 2. The manufacturer’s standard painting system and standard colour are acceptable for transformers located in a mechanically ventilated area.