Answer / raghavendran.r

An LCI drive using SCRs does not need extra forced turn-off and does not use PWM to vary the frequency. It uses SCRs on the front-end to covert the incoming AC to variable voltage DC, then uses multiple SCRs on the back end to fire into the motor at a varying frequency, but relies upon the motor's rotation itself to make the current passing through the SCRs to cross through zero and turn off (hence the term "Load Commutated"). This is done through very complex firing schemes that require a relatively high powered computer to accomplish. That's why you will not see LCI drives on small motors; the cost is prohibitive and LCI drives cannot compete with PWM where PWM is effective and reliable. But on very large synchronous motors the transistor technology becomes a quantum leap more expensive and highly susceptible to damage, so LCI drives start to make sense again.

What are the main problems in distribution? I have to do an assignment so which problem should I choose? Like power factor problem etc.

4 Answers  

---

what is the relevance of knee point voltage in protection and metering grade CT ? and basically what is knee point voltage ?

2 Answers  

---

Why not connect relay Y phase for over current and earth fault

1 Answers   HB,

---

Where earth point should provided in Ships or Submirines.

2 Answers   SSC,

---

What are the properties of a resistor?

0 Answers  

---

How do you calculate of power factor, if it is lagging or leading for unit(1).

4 Answers  

---

can anybody sent me power grid questions. what subject should i prefer for preparation?

0 Answers   Reliance, Vascon,

---

explain different types of d.c motors?

0 Answers  

---

what are ABCD curves in MCBs and how we observe that curves?

2 Answers  

---

Where the excitation is given either stator or rotor in actually in power plants?

13 Answers  

---

what is the function of choke in a tubelight

3 Answers  

---

Where r use in Dc motor in power plant?

2 Answers  

---