Answer / vipul jain

In the case starter, the capacitors are often controlled by
the main contactor which is also controlling the motor.
This is because the capacitance and the inductance of the
motor form a resonant circuit. While the motor is connected
to the supply, there is no problem. Once the motor is
disconnected from the supply, it begins to decelerate. As it
decelerates, it generates voltage at the frequency at which
it is rotating. If the capacitive reactance equals the
inductive reactance, i.e. unity power factor, we have
resonance. If the motor is critically corrected (pf = 1) or
over corrected, then as the motor slows, the voltage it is
generating will pass through the resonant frequency set up
between the motor and the capacitors. If this happens, major
problems can occur. There will be very high voltages
developed across the motor terminals and capacitors causing
insulation damage, high resonant currents can flow, and
transient torque's generated can cause mechanical equipment
failure.

Answer / g.v.hema chandu

The unity power factor means the angle b/w voltage and current is unity.As a practical it is not possible for motors because motor is inductive.For an theory if motor is at unit power factor the speed decreases.

Please nybody say, weather the result of Bharat Oman is declared or not? Probable date of declare???????

0 Answers  

---

What is the breakdown voltage?

13 Answers  

---

What is Skin effect of the cable?

8 Answers   L&T,

---

Why a Permanent Magnet Generator has higher frequency as compared to frequency of main alternator?

0 Answers  

---

What is warm / cold start of HT motors. How many warm start & cold start are possible in a day?

0 Answers  

---

i wanna know that star point in transformer becomes as a neutral on secondary side now tell me that how is that possible?because if joit the all three winding ends with each other it can b short circuited.dut it doesn't.WHY?pls Answer me in brief.thanks alot

1 Answers  

---

one hp 3phase motor what generate power factor

1 Answers  

---

What is power factor? Whether it should be high or low ? why?

9 Answers  

---

my diploma certificate in my higher education college

0 Answers   Aastha Spintex,

---

how to set the time in digital timer ?

0 Answers  

---

How many 2 ton window A/c can runs on a 125 KVA generator?

2 Answers  

---

If we want to change a contactor of faulty one what are the conditions want to fullfil

0 Answers   Qatar Shell,

---