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 is the effect on 3phase induction motor if current setting knob of DOL kept at minimum current?

0 Answers  

---

What is the diameter of electromagnetic field around a 11000/415v transformer ? Dose it affect people who live 3-4 meter beside it?

0 Answers  

---

What is meant by Active and reactive power?

5 Answers   Siemens,

---

diff between UPS and inverter?

2 Answers  

---

Does the ELCB or RCCB trip when it is connected to a primary side of a welding transformer?

3 Answers   Tata Motors,

---

---

Why the tank of transformer is made rectangular not circular??

9 Answers  

---

In PFI plant one stage capacitor connection is directly connected(with out megnetic contact controll). but why?

0 Answers   Aegis,

---

What is class X ct? What rare its uses?

2 Answers  

---

How to Select a Transformer Rating ?

3 Answers   Tata Steel Limited, Techno Electric and Engineering, Vedanta,

---

We have got the HT connection of 1000 KVA in which we have installed a seprate APFC panel at the PCC end & seprate KWH meter is installed. My question is that does the KWH reading shown in the meter is a part of the Consumption ???? ( approx 500 units is shown)

1 Answers  

---

what is mean by parallel operation of permanent magnet generators

0 Answers   PSD,

---

give single line diagram of D.O.L and star -Delta starter ?

8 Answers   ABS, Al-Shuaah, Alkali Metals, Cabin Crew, Cognizant, CRI, Gwalior Distilleries, Hotels, Logicon Engineers, Max India, Nicomet, Radisson Blu, RK Company, Siemens, SLCM, Solar, Steel Strips Wheels, Sugar Factory, TATA, TCS,

---