Description : For large power transformers, self oil cooled type or air blast type which of the following values of current density may be used ? (a) 1.0 to 1.2 A/mm2 (b) 1.5 to 2.0 A/mm2 (c) 2.2 to 3.2 A/mm2 (d) 3.2 to 4.2 A/mm2
Answer : (c) 2.2 to 3.2 A/mm2
Description : Suggest the type of cement used for the following : (i) For modular construction where form work needs to be removed early for re-use. . (ii) Mass concreting such as construction of dam. (iii) Decorative works in external surfaces of building. (iv) Cementing the oil well.
Answer : i) For modular construction where form work needs to be removed early for reuse. – Rapid Hardening Cement ii) Mass concreting such as construction of dam. – Low heat cement. iii) Decorative works in external surfaces of building – Coloured cement. iv) Cementing the oil well. – Oil Well Cement.
Description : 76 The changes in volume of transformer cooling oil due to variation of atmospeheric temperature during day and night is taken care of by which part of transformer? A. Conservator B. Breather C. Bushings D. Buchholz relay
Answer : A. Conservator
Description : 1] A Buchholz relay can be installed on A. Auto-transformers B. Air-cooled transformers C. Welding transformers D. Oil cooled transformers
Description : A current density of _____ is ilsed for large power transformers with forced circulation of oil or with water cooling coils (a) 1.5 to 2.5 A/mm2 (b) 3.5 to 4.5 A/mm2 (c) 4.0 to 5.0 A/mm2 (d) 5.4 to 6.2 A/mm2
Answer : (d) 5.4 to 6.2 A/mm2