EX-404
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IES COLLEGE OF TECHNOLOGY, BHOPAL B.E. (EX 4th Semester) MID SEM-1 Electrical Machine -I (EX-404) Maximum Marks: 40 Minimum Pass Marks: 15 Note:-Attempt all questions. Times: 2 Hours. Unit 1 (a) Does the transformer draw any current when it’s secondary open?(June 204) (b) Is cu losses affected by power factor and load current? ( Dec 2013) (c) Derive the e.m.f. equation of single phase transformer. (June 2014) 2 2 3 7 Unit 1 (a) What part of the transformer, in which conducting material is used?(June 2012) (b) Under what conditions, a transformer is called ideal transformer? (Dec 2014) (c) A 20 kVA, 440/220 V, 1-phase, 50 Hz transformer has iron loss of 324 W. The Cu loss is found to be 100 W when delivering half full load current. Determine (i) efficiency when delivering full load current at 0.8 lagging p.f. and (ii) the percent of full load when the efficiency will be maximum. ( June 23014) (d) Obtain the equivalent circuit of a 200/400 V, 50 Hz, 1- 2 2 3 7 Unit II (a) As compare to Delta-Delta bank, capacity of the V-V bank of transformer is what percent. (b) Write down the advantages of three single phase transformer as compare to single three phase transformer? (June 2012) (c) Two 1-phase transformers A and B rated at 250 kVA each are operated in parallel on both sides. Percentage impedance for A and B are (1+ j6) and (1.2+j4.8) respectively. Compute the load shared by each when the total load is 500 kVA at 0.8 2 2 3 7
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IES COLLEGE OF TECHNOLOGY, BHOPALB.E. (EX 4th Semester) MID SEM-1Electrical Machine -I (EX-404)Maximum Marks: 40 Minimum Pass Marks: 15Note:-Attempt all questions. Times: 2 Hours.Unit 1(a) Does the transformer draw any current when its secondary open?(June 204)(b) Is cu losses affected by power factor and load current? ( Dec 2013)(c) Derive the e.m.f. equation of single phase transformer.(June 2014)(d) A 600 kVA, 1-phase transformer has an efficiency of 92 % both at full load and half load at unity power factor. Determine its efficiency at 60 % of full load at 0.8 power factor lag. (Dec 2012) ........) .......................................( RGPV .......) ...................................... (RGPV .......) 22
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Unit 1(a) What part of the transformer, in which conducting material is used?(June 2012)(b) Under what conditions, a transformer is called ideal transformer? (Dec 2014)(c) A 20 kVA, 440/220 V, 1-phase, 50 Hz transformer has iron loss of 324 W. The Cu loss is found to be 100 W when delivering half full load current. Determine (i) efficiency when delivering full load current at 0.8 lagging p.f. and (ii) the percent of full load when the efficiency will be maximum. ( June 23014)(d) Obtain the equivalent circuit of a 200/400 V, 50 Hz, 1-phase transformer from the following test data:O.C. test : 200 V, 0.7 A, 70 W on L.V. sideS.C test : 15 V. 10 A, 85 W- on H. V side Calculate the secondary voltage when delivering 5 kW at 0.8 p.f. lagging, the primary voltage being 200V. 223
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Unit II(a) As compare to Delta-Delta bank, capacity of the V-V bank of transformer is what percent.(b) Write down the advantages of three single phase transformer as compare to single three phase transformer? (June 2012) (c) Two 1-phase transformers A and B rated at 250 kVA each are operated in parallel on both sides. Percentage impedance for A and B are (1+ j6) and (1.2+j4.8) respectively. Compute the load shared by each when the total load is 500 kVA at 0.8 p.f. lagging. ( June 2011)(d) A 3-phase delta/star connected 11000/440 V, 50 Hz transformer takes a line current of 5 amp, when secondary load of 0.8 lagging p.f. is connected. Determine each coil-current and output of transformer. (Dec 2010)
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