1- The primary and secondary of a transformer are -------- coupled.a) Electrically b) magnetically c) clectrically and magnetically d) none of the previous.2- A transformer absorbs 62.5W when the primary is connected to its normal supply of250V, 50Hz; the secondary being on open circuit. The value of R, isa) 100 b) 452 c) 200012 d) 10002 e) none of the previouswww‒‒‒3- A transformer will have zero efficiency at --------a) Full-load b) half-load c) no-load d) none of the previous.4- A transformer has an iron loss of 100W at 40Hz and130W at 50Hz then theapproximate value of the iron loss at 75 Hz is. The flux density is constant.a) 114 W b) 134 W c) 214 W d) none of the previous5- 10 kVA, 250/500V, 50Hz single phase transformer, the flux density is 1.1 Wb/m² and thevoltage per turn in the primary is 2V then the voltage per turn on the secondary is-a) 4V b) 2V c) 6.1V d) none of the previous6- A transformer has 200 W as an iron loss at full load. The iron loss at half-load will be(a) 50W b) 100W c) 400W d) none of the previous.

Based on the bartleby guidelines solved the first three questions. 1. Answer: Magnetically…

- coupled. 1- The primary and secondary of a transformer are ---..... a) Electrically b) magnetically c) clectrically and magnetically d) none of the previous. 2- A transformer absorbs 62.5W when the primary is connected to its normal supply of 250V, 50Hz; the secondary being on open circuit. The value of R, is a) 1000 b) 42 c) 20002 d) 10002 e) none of the previous 3- A transformer will have zero efficiency at --------- a) Full-load b) half-load c) no-load d) none of the previous. 4- A transf

- coupled. 1- The primary and secondary of a transformer are ---..... a) Electrically b) magnetically c) clectrically and magnetically d) none of the previous. 2- A transformer absorbs 62.5W when the primary is connected to its normal supply of 250V, 50Hz; the secondary being on open circuit. The value of R, is a) 1000 b) 42 c) 20002 d) 10002 e) none of the previous 3- A transformer will have zero efficiency at --------- a) Full-load b) half-load c) no-load d) none of the previous. 4- A transf

Power System Analysis and Design (MindTap Course List)

6th Edition

ISBN:9781305632134

Author:J. Duncan Glover, Thomas Overbye, Mulukutla S. Sarma

Publisher:J. Duncan Glover, Thomas Overbye, Mulukutla S. Sarma

Chapter3: Power Transformers

Section: Chapter Questions

Problem 3.58P: A single-phase two-winding transformer rated 90MVA,80/120kV is to be connected as an autotransformer...

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Similar questions

Consider Figure 3.25 of the text for a transformer with off-nominal turns ratio. (i) The per-unit equivalent circuit shown in part (c) contains an ideal transformer which cannot be accommodated by some computer programs. (a) True (b) False (ii) In the - circuit representation for real c in part (d), the admittance parameters Y11 and Y12 would be unequal. (a) True (b) False (iii) For complex c, can the admittance parameters be synthesized with a passive RLC circuit? (a) Yes (b) No
A single-phase 100-kVA,2400/240-volt,60-Hz distribution transformer is used as a step-down transformer. The load, which is connected to the 240-volt secondary winding, absorbs 60 kVA at 0.8 power factor lagging and is at 230 volts. Assuming an ideal transformer, calculate the following: (a) primary voltage, (b) load impedance, (c) load impedance referred to the primary, and (d) the real and reactive power supplied to the primary winding.
Consider Figure 3.4. For an ideal phase-shifting transformer, the imda nce is unchanged when it is referred from one side to the other. (a) True (b) False
The transformer of Problem 3.16 is supplying a rated load of 50 kVA at a rated secondary voltage of 240 V and at 0.8 posr factor lagging. Neglect the transformer exciting current. (a) Determine the input terminal voltage of the transformer on the high-voltage side. (b) Sketch the corresponding phasor diagram. (c) If the transformer is used as a step-down transformer at the load end of a feeder whose impedance is 0.5+j2.0, find the voltage VS and the power factor at the sending end of the feeder.
Consider a source of voltage v(t)=102sin(2t)V, with an internal resistance of 1800. A transformer that can be considered as ideal is used to couple a 50 resistive load to the source. (a) Determine the transformer primary-to-secondary turns ratio required to ensure maxi mum power transfer by matching the load and source resistances. (b) Find the average power delivered to the load, assenting maximum power transfer.
A single-phase two-winding transformer rated 90MVA,80/120kV is to be connected as an autotransformer rated 80/200kV. Assume that the transformer is ideal. (a) Draw a schematic diagram of the ideal transformer connected as an autotransformer. showing the voltages, currents, and dot notation for polarity. (b) Determine the permissible kVA rating of the autotransformer if the winding currents and voltages are not to exceed the rated values as a two-winding transformer. How much of the kA rating is transferred by magnetic induction?
A single-phase 50-kVA,2400/240-volt,60-Hz distribution transformer is used as a step-down transformer at the load end of a 2400-volt feeder whose series impedance is (1.0+j2.0) ohm. The equivalent series impedance of the transformer is (1.0+j2.5) ohms referred to the high-voltage (primary) side. The transformer is delivering rated load at a 0.8 power factor lagging and at a rated secondary voltage. Neglecting the transformer exciting current, determine (a) the voltage at the transformer primary terminals, (b) the voltage at the sending end of the feeder, and (c) the real and reactive power delivered to the sending end of the feeder.
An ideal transformer has no real or reactive power loss. (a) True (b) False
Consider an ideal transformer with N1=3000andN2=1000 turns. Let winding 1 be connected to a source whose voltage is e1(t)=100(1| t |)volts for 1t1ande1(t)=0 for | t |1 second. A2- farad capacitor is connected across winding 2. Sketch e1(t),e2(t),i1(t),andi2(t) versus time t.
An infinite bus, which is a constant voltage source, is connected to the primary of the three-winding transformer of Problem 3.53. A 7.5-MVA,13.2-kV synchronous motor with a sub transient reactance of 0.2 per unit is connected to the transformer secondary. A5-MW,2.3-kV three-phase resistive load is connected to the tertiary Choosing a base of 66 kV and 15 MVA in the primary, draw the impedance diagram of the system showing per-unit impedances. Neglect transformer exciting current, phase shifts, and all resistances except the resistive load.
For the transformer in Problem 3.10. The open-circuit test with 11.5 kV applied results in a power input of 65 kW and a current of 30 A. Compute the values for GcandBm in siemens referred to the high-voltage winding. Compute the efficiency of the transformer for a load of 10 MW at 0.8 p.f. lagging at rated voltage.
A three-phase transformer is rated 1000MVA,220Y/22kV. The Y-equivalent short-circuit impedance, considered equal to the leakage reactance, measured on the low-voltage side is 0.1. Compute the per-unit reactance of the transformer. In a system in which the base on the high-voltage side of the transformer is 100MVA,230kV what value of the per-unit reactance should be used to represent this transformer?