Indepth Electrical engineering

Technical Specifications for  400 kVA, 11 kV/433V  Oil-Immersed Distribution Transformer 1. General Requirements Type: Double copper wound, three phase, oil immersed, ONAN cooled Rating: 400 kVA Primary Voltage: 11 kV Secondary Voltage: 433 V Frequency: 50 Hz ± 5% Supply Voltage Variation: ±10% Vector Group: Dyn11 2. Electrical Parameters Impedance (at 75 °C): 5% No-load losses (max): 0.7 kW Full-load losses (max): 5.1 kW Short circuit withstand: 3 sec at 5% impedance Harmonic suppression: 3rd, 5th, 7th harmonics + high-frequency disturbances 3. Thermal Limits Oil temperature rise: ≤ 35 °C over ambient (40 °C) Winding temperature rise: ≤ 40 °C over ambient (40 °C) 4. Insulation & Withstand Levels Power frequency withstand (1 min): 3 kV (433 V side) 28 kV (11 kV side) Lightning impulse withstand: 75 kVp (11 kV side) 5. Tap Changer HT side off-load tapping: ±5% in steps of 2.5% 6. Design Clear...

Transformers are backbone of electrical systems. Transformers are used for both stepping up and stepping down the voltage. While procurement of  Distribution Transformers there are following technical aspects which should be considered :- For Tan-delta, Loss angle test visit link:- http://electrialstandards.blogspot.com/2015/10/tan-delta-test-loss-angle-test.html Below are the technical specifications of Oil type 990 KVA transformer :- 1.        Transformer voltage ratio should be 11 KV/ 433 V 2.        Vector group should be Dyn11 3.        Transformer Impedance at 75 degree Celsius should be 5% 4.        Transformer maximum no load losses should 1.4 KW 5.        Transformer Maximum full load losses should be 10.8 KW 6.        Transformer Oil Temperature rise without enclosure ...