Answer / romesh roy nigam

Cogging - The rotar of squirral cage motar some times
refuse to start at all,particularly when the voltage is low
this when number of rotar teeth becomes equal to numbers of
stator teeth & due to magnatic locking between stator and
rotar teeth.
Crawling - The phenomenon when squirral cage motar some
times showing tendency to run stably at speed as low as one
seventh of its synchronus speed

Answer / raul

COGGING : when the stator and rotor poles of a 3-phase
Induction motor r either equal or have an integral
ratio......there is a strong alignment or magnetic locking
b/w the stator n rotor teeths.......so due to this the
motor is unable to start inspite of applying full rated
voltage across the motor........
CRAWLING : it is inability of a 3-phase induction motor to
speed up to desired slip speed and has a tendency to run at
a stable speed of 1/7th of the synchronous speed. this
normally occurs due to the 7th harmonic present in the non-
sinusoidal flux wave.......it can be avoided by using short
chorded windings.......

What is the effect of positive feedback on the stability of the systems?

0 Answers  

---

why is the earthing pin on 3 pin top are big and thick

3 Answers   Marriott,

---

Utility company give the supply to customer in KVA but bill them for Watt.why?

1 Answers   L&T,

---

DIFFERENCE BETWEEN NORMAL TRAFO AND THRISTER TRAFO?

0 Answers   Essar, MahaGenco,

---

Transmission line design. Say, I have a 1MVA generator and 2 transformers that will have the same load. What would be the proper rating of the trasformers? Is it safe to say, that I will simply divide the total rating of the generator?

1 Answers  

---

What is infinite Busbar?

4 Answers   Equate,

---

what is voltage,current,restance,. what is single phase&three phase motar. what is basic electrical 'farmoulas. what is defirens quetions of electrical maintenance.

2 Answers  

---

Explain about p.t?

0 Answers  

---

why ohms law does not obey semi-conducters?

2 Answers  

---

what's the meaning of the negative going half cycle in the circuit containing a bulb and a switch in series with a input ac source. i mean what happens in the -ve cycle. the dir. of current changes or any other thing. if dir. changes then why we use fuse in only phase wire.

2 Answers  

---

Why it is necessary to isolate fire fighting when you are taking shutdown for lv board.

0 Answers   KSEB, L&T, Siemens,

---

What about Reactive power.and role of that one?

7 Answers  

---