Transformers Objectives Part 02
21 . Essential condition for the parallel operation of a transformer is they must operate at the same frequency
22 . 1 KVA , 25 Hz transformer will be largest in size.
23 . A step up transformer increased voltage
24 . In a step down transformer the secondary turns are less than the primary turns.
25 . Power transformer are usually designed to have maximum efficiency near full load.
26 . Distribution transformer are usually designed to have maximum efficiency near 50% of full load.
27 . Iron loss of a transformer can be approximately calculated if the weight of core and yoke is known.
28 . In high frequency transformer ferrite cores are used.
29 . Open circuit test on a transformer yields core losses.
30 . The leakage flux in a transformer depends upon load current.
31 . Radio interference test is not a routine test on transformer.
32 . A transformer will have the highest efficiency near 93% of rated load.
33 . A 1KVA transformer at full load will have transformer
34 . The sum of all losses in a 1 KVA transformer at full load will be order of 50W
35 . In a transformer the peak voltage is fed to primary the iron losses will be less
36 . The phase difference between the primary and secondary voltage of a transformer is 180
37 . In a transformer the copper loss at half load as compared to that at full load will be one fourth.
38 . The path of the magnetic flux in transformer should be high reluctance
39 . The desirable properties of transformer core material are high permeability and low hysteresis.
40 . Core losses in a transformer vary from 1% to 3% between no load and full load.