Questions for 18 March 2016

                         Problem Based on Transformer

Q:-1 A 100kVA, 2400/240 V, 50Hz single phase transformer has no load current of 0.64A and core loss of 700watt , when excited from its high voltage side at rated voltage and frequency. Calculate the component of no load current and no load branch parameters.
Q:-2 The ohmic values of circuit parameters of a transformer having a turn ratio of 5, are R1=0.5Ω, R2=0.021Ω, X1=3.2Ω and X2=0.12Ω. The R0=350Ω and X0=98Ω referred in primary side. Draw the approximate equivalent circuit diagram of transformer referred in secondary side with numerical values.
Q:-3 The maximum efficiency of a 100 kVA, 1100/440 V, 50Hz transformer is 96%.This occurs at 75% of full load at 0.8 power factor lagging. Find the efficiency of transformer at ¾ of full load at 0.6 power factor leading.
Q:-4 The efficiency of a 400kVA, single phase transformer is 98.77% at full load 0.8 power factor and 99.13% at half full load unity power factor. Find (i) Iron losses at full and half full loads (ii) Cu losses at full and half full loads.
Q:5A  single-phase 400 V, 50 Hz transformer has an iron loss of 5000 W at the rated condition. When operated at 200 V, 25 Hz, the iron loss is 2000 W. When operated at 416 V, 52 Hz, the value of the hysteresis loss & eddy current loss is......


Answers will published on 19 March 2016.