According to IS (Indian Standard) specification 1180-1964 for outdoor type distribution transformer, the tapings shall be provided on hv side in _______.

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SSC JE Electrical 10 Oct 2023 Shift 2 Official Paper-I

Answer 1

IS Specifications for Outdoor type distribution transformers (IS : 1180-1964)

1.) Standard ratings: 16, 25, 40, 50, 63, 80 and 100 kVA

2.) No-load voltage ratios: 3300/433 V, 6600/433 V and 11000/433 V

3.) Tappings: Shall be provided on the hv side in 5 steps. The ranges shall be ± 2.5% and + 5% off-load tap changers to be used.

4.) Connections: LVY (Dy 11) with neutral brought out to a separate insulated terminal.

5.) Cooling: By low-viscosity transformer oil

6.) Conservator tank: To be provided on transformer of rating 50 kV or above

7.) Limits of temperature rise:

The following temperature rises shall be permitted over the ambient temperature of 45°C
Winding (temperature to be measured by resistance method) 55°C
Oil (temperature rise to be measured by thermometer in the top oil) 45°C
The above temperature rises are for ON, OB, OW type cooling