Answer / raul

When the dc supply is given to the rotor windings, then the
polarity of the north and south poles will be fixed in the
space and time, so a sinusoidal magnetic field/flux will be
set up in the air gap which in turn will cut the stator
conductors and hence as per the lenz's law, there will be
induced emf and consequently induced currents in the stator
conductors.

But if ac supply is provided to the rotor windings, then
the polarity of the north and south poles will not be fixed
and it will keep on varying as per the sinusoidal curve, so
a sinusoidal field/flux will not be created in the air gap,
no flux cutting of the stator conductors and hence no
current in the stator windings. That is why the rotor
windings are not provided with the ac supply.

Answer / guest

in case of ac supply the current will vary
alternatively,its value varies from zero,+ve max,zero,-ve
max .so u will get zero magnitude of magnetic field for one
cycle.so u cant cut stator with flux,so there is no induced
emf in stator. finally no output from stator.but in dc
exicitation u will get net magnetic field.and u will get
induced emf.

What is the full form of AND,OR and other logic gates

7 Answers  

---

why ct ratio always rated 5.

1 Answers  

---

for 11KV OH system what will be typical per KM "R" "L" "C" parameter. for 33KV OH system what will be typical per KM "R" "L" "C" parameter. for 33KV UG system what will be typical per KM "R" "L" "C" parameter.

0 Answers   wbsedcl,

---

how to find 5 kilo meter long under ground 33 kv cable fault location if IR VALUE shows 0.05 M ohm @5000 volt.and cable fault locator shows some time fault distance 3 kilo meter ,3.7 kilo meter and some time 1 kilo meter? now how to find the fault location that where is leakage.

1 Answers   FGI, OPS,

---

why an ac solenoid valve attract the plunger eventhough we interchanges the terminal?will the ploes changes?

1 Answers  

---

How can remove the jerks on genretor due to remov or connecting the load ?

3 Answers  

---

What is the difference between Neutral and Earth

6 Answers   Bhel,

---

why odd hormonics only will effect the power system.why not even hormonics

1 Answers  

---

Why r used of cable 50sq.mm and above size cable in 3.5 core. And below size in 4 core ? any technical reason please explain it

2 Answers  

---

if we supply DC power to AC transformer then what its result?

15 Answers  

---

i have a motor 55kw how u will calculate cable specification for this motor

1 Answers  

---

draw waveform of capacitor or inductor in a d.c ckt(during transient) with zero resistance with it(in series or parallel)also neglect resistance of wire

2 Answers   L&T,

---