Name: Assignment of Advanced Electrical Machine
Uploaded: 2023-03-20
Duration: 4 min 50 s
Description: Assignment of Advanced Electrical Machine. Teacher Name: Prof Syed Qurban Ali Shah By Mudasir Larik Roll No: L-20EL-17 Dated : 20/03/23.

Assignment of Advanced Electrical Machine. Teacher Name: Prof Syed Qurban Ali Shah By Mudasir Larik Roll No: L-20EL-17 Dated : 20/03/23. 

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Assignment of Advanced Electrical Machine

Teacher Name:  Prof Syed  Qurban  Ali Shah  By  Mudasir Larik   Roll No:  L-20EL-17 Dated : 20/03/23

Q;1 Is the turn ratio of a transformer the same as the ratio of voltage across the transformer ? Why or why not ?. 

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Q;1  Is the turn ratio of a transformer the same as the ratio of voltage across  the transformer ? Why or why not ?

It is observed that ratio of voltages of transformer are same as ratio of their turns because flux linking both the coils is same. So, voltage will be directly proportional to number of turns .

Q;2 why does the magnetization current impose an upper limit on the voltage applied to a transformer core ?. 

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Q;2  why does the magnetization current impose an upper limit on the voltage applied to a transformer core ?

The magnetization current( im ) which is the current required to produce the flux in the transformer core . Q;3   what components compose the excitation current of a transformer ? How are they modeled in transformer’s equivalent circuit ?  Magnetization lag voltage applied to core by 90° degrees  Higher frequency component  No load current .

Q ;4 what is leakage flux in a transformer ? Why is it modeled in transformer as equivalent circuit in inductor ?. 

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Q ;4  what is leakage flux in a transformer ? Why is it modeled in transformer as equivalent circuit in inductor ?

Flux leakage  ϕ Lp  and  ϕ Ls  in the transformer winding are the leakage flux. Flux produce self inductance in coil , inductance must be accounted for coils .

Q;5 List and describe the types of losses occur in transformer ?. 

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Q;5  List and describe the types of  losses occur in transformer ?

Copper losses ;   (I 2 R) copper losses are the resistive heating losses in the primary and secondary winding of transformer  Eddy current losses ; eddy current losses are the resistive current losses in the core of the transformer.   Hysteresis  losses   ; hysteresis losses are associated with the rearrangement of the magnetic domain in the core.

Q;6 Why does the power factor of a load affect the voltage regulation of a transformer ?. 

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Q;6 Why does the power factor of a load affect the voltage regulation of a transformer ?

Voltage at full load is defined by  eq ;   Q 7; Why does the short circuit test essentially show only I2R losses and not excitation losses in transformer ?  To can calculate value of RC and  Xm  First at admittance of excitation branch. core losses resistor is given by  Gc =1/RC BM = 1/ xm  .

Q;8. Why does the open-circuit test essentially show only excitation losses and not PR losses?. 

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Q;8. Why does the open-circuit test essentially show only excitation losses and not PR losses?

In open- winding is Circuit open- test secondary Circuit on the Primary connected full rated is Line voltage. Input current through  exi  must  encitation  transformer. be branch flowing of transformer   Q ;9  How does the per-unit system of measurement eliminate the problem of different voltage levels in a power system? These are the problems per unit system ;

Q;10 How does the per-unit system of measurement eliminate the problem of different voltage levels in a power system?. 

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Q;10 How does the per-unit system of measurement eliminate the problem of different voltage levels in a power system?

Because voltage at secondary is lower than voltage at primary so VR>0 .   Q11;What are transformer taps? Why are they used? The tops on a transformer permit the transformer - to be adjusted in the field to accommodate variations in local Voltages. why are used?  Sometimes transformer is used - power line whose voltage Varies widely with the load.

Q12; What are the problems associated with the Y-Y three-phase transformer connection ?. 

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Q12; What are the problems associated with the Y-Y three-phase transformer connection ?

Load on Transformer circuit are unbalanced voltage phase of it will be unbalanced. Harmonic voltage can be large . Q13;What is a TCUL transformer? A TCUL transformer is a transformer with the ability to change taps while. power is connected to it .

Q14;How can three-phase transformation be accomplished using only two transformers What types of connections can be used? What are their advantages and disadvantages?. 

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Q14;How can three-phase transformation be accomplished using only two transformers What types of connections can be used? What are their advantages and disadvantages?

It can be three single transformer accomplished to three-phase bank. Three and phase connect in phase transformer consists of three set I wrapped on Cove a of winding common core . Disadvantage: Three single phase unit in Service Advantage :Unit in bank is by trouble replaced.

Q15 Explain why the open-A transformer connection is limited to supplying 57.7 percent of a normal Δ - Δ transformer bank's load.. 

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Q15 Explain why the open-A transformer connection is limited to supplying 57.7 percent of a normal  Δ -  Δ  transformer bank's load.

This one Transformer is producing reactive power  which the other one is consuming. It is this exchange of energy between two transformers that limits the power output to 57.7 percent of the original banks rating instead of the other wise expected 66.7 percent. An alternative way. to look at the rating of the open-delta connection is that 86.6 percent) of the rating of the two remaining transformer can be used.

Q;16 Can a 60-Hz transformer be operated on a 50-Hz system? What actions are necessary to enable this operation?. 

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Q;16 Can a 60-Hz transformer be operated on a 50-Hz system? What actions are necessary to enable this operation?

Yes one is protected winding insulation from breakdown due to voltage magnetization curve and magnetization current of transformer.  Q;17    What happens to a transformer when it is first connected to a power line? Can any- thing be done to mitigate this problem? The power supplied by transformer secondary circuit to its load is given by  eq ;

Q;18What is a potential transformer? How is it used?. 

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Q;18What is a potential transformer? How is it used?

Transformer has  pon  high primary voltage and Low voltage secondary, It has low power rating. Principle purpose of trans farmer is voltage sampling . P.T;  The Potential Transformer of a several accuracy. Q19 .  What is a current transformer? How is it used? Current Transformer (CT) sample the current in line and reduce it to be measurable level. The(C,T) windings wrapped around a ferromagnetic ring with single primary winding though center of ring A (CT)  diffences  from other transformer describe in chapter its winding  are closely coupled.

Q;20 A distribution transformer is rated at 18 kVA, 20,000/480 V, and 60 Hz. Can this transformer safely supply 15 kVA to a 415-V load a 50 Hz? Why or why not?. 

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Q;20 A distribution transformer is rated at 18 kVA, 20,000/480 V, and 60 Hz. Can this transformer safely supply 15 kVA to a 415-V load a 50 Hz? Why or why not?

NoSolve   (It reduce voltage  Exp : 110 to 2201). Does not reduce voltage in KVA . Distribution  transformer have not rating in KVA. Q;21Why does one hear a hum when standing near a large power transformer? And we can hear an audible hum in a transformer because electric currents affect its internal structure and cause vibrations. The buzzy tone this creates can be referred to as 'mains hum' and is ever present, although not always perceptible to the human ear.

Assignment of Advanced Electrical Machine

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