1.1 The transformer shall be three-phase, two winding, 60 Hz, outdoor, oil-immersed type. 1.2 The transformer shall have the following ratings as shown in the table below: Rating Criteria HIGH-VOLTAGE H-WINDING LOW VOLTAGE X-WINDING Nameplate Rating at 65 C Rise (MVA) 90/120/150 Nominal System Voltage (line-to-line) (kV) 345 13.8 Transformer connections (wye or delta) Wye Delta Tap changer – taps to be manually changed when transformer is not excited: See below. Above rated voltage at full MVA capacity (Number of taps and percent volts each tap) 2 – 2.5% Below rated voltage at full MVA capacity (Number of taps and percent volts each tap 2 – 2.5% System neutral (isolated or type of grounding) Solidly Grounded Gen Neutral Grounded through Dist. Transformer Basic lightning impulse insulation level (BIL) (KV) 1050 110
