1. A no-load test is performed on a transformer to determine
(a). Core loss (b). Copper loss
(c). Efficiency (d). Magnetising current and loss
Ans.d
2. For a transformer, the condition for maximum efficiency is
(a) Hysteresis loss = eddy current loss
(b) Core loss = hysteresis loss
(c) Copper loss = Iron loss
(d) Total loss = 2/3 copper loss.
Ans.c
In Transformer maximum efficiency =2*Iron loss
So here Iron loss = to Copper loss
(Max,Efficiency=Cu loss+Iron loss)
So here Iron loss = to Copper loss
(Max,Efficiency=Cu loss+Iron loss)
3. In a transformer the tappings are generally provided on
(a). primary side (b). secondary side
(c). low voltage side (d). high voltage side
Ans.c
4. Transformer oil shall be free from
(a) Odour (b) Gases
(c) Temperature (d) Moistur
Ans.d
5. The colour of fresh dielectric oil for a transformer
(a) Pale yellow (b) Dark brown
(c) White to grey (d) Colourless
Ans.d
6. The function of breather in a transformer is
(a). to provide oxygen inside reduced load
(b). to cool the coils during reduced load
(c). to cool the transformer oil
(d). to arrest flow of moisture when outside air enters the transformer
Ans.d
7. The maximum efficiency of a distribution transformer is
(a). at no load (b). at 50% full load
(c). at 80% full load (d). at full load
Ans.b
8. Material used for construction of transformer core is usually
(a). Wood (b). copper
(c). Aluminium (d). silicon steel
Ans.d
9. An open-circuit test on a transformer is conducted primarily to measure
(a). Insulation Resistance (b). Copper loss
(c). Core loss (d). Total loss
Ans.c
10. A Buchholz relay can be installed on
(a). auto-transformers (b). air-cooled transformers
(c). welding transformers (d). oil cooled transformers
Ans.d
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