Answer / iamdon

The rotor is a structure having mass and elasticity.So it
will vibrate with a natural fcrequency which is balanced by
elastic force.The mass centre has an inherent eccentricity
from the centre of rotation.

The deflection tend to be very large near or at critical
speed and gives rise to considerable vibrations.This may
break the shaft.That is why rotating machines are not
allowed to run near or at critical speed.

Author:arbelectbit@yahoo.com

Answer / s.krishnan

critical speed is above 20 percentage of rated
speed.rotating machine rotate near to critical speed the
motor bearings are damaged.so rotating machines are not
allowed to run near critical speed region.

How to select transmission line type (i.e. 11kv or 33kv) for new established industries

0 Answers  

---

3phase motor can be used as a Prime mover for alternator.

0 Answers  

---

what is the meaning of the symbol << >> put in transformer drawing

0 Answers   TATA,

---

What happens if fuse is connected to neutral wire

9 Answers   HAL,

---

How can Inductive load reduce the line voltage of HV transmission line and vice versa Capacitive load?

1 Answers  

---

How we select the cable rating

1 Answers   BTM, Videocon,

---

what is the significance of per unit impedance ?

7 Answers   HP,

---

Why mostly GT(Generating Transformer)has only Ynd1 Vector Group?

1 Answers   Essar,

---

Why L.T.Cable voltage rating is 1.1kV,where as system voltage is 0.415kV?

0 Answers   HCC,

---

Why do we use only Sinusoidal Wave in AC supply why not the Square,Triangle or Sawtooth etc?

2 Answers  

---

Give me the calculation steps to design an electromagnet to be work in 230V 50 Hz AC Supply. Also give force that is created by that electromagnet when it gets energized.

0 Answers   GE,

---

What are the Return ( Monthly / quarterly/ Annual submitted to Electical Inspector for an establishment (Factory in Maharashtra-- Small scale category having seperate HT line of 22KV ) as per Maharashtra Electricity Act

0 Answers  

---