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.

why we use condenser in the thermal power plant, althrough the same vapour will be again heated

0 Answers   Bhel,

---

How will A Medium voltage circuit breaker(11 kV voltage level) operate under short circuit fault condition whether It is having short circuit release like Low voltage circuit breaker or relay should be given?

0 Answers  

---

Good day everyone,currently in our premise we using 30kw slip ring motor with resistance bank which we use as forward and reverse at conveyor bar handling. So,my question is how do we calculate the resistance bank which is suit the motor. Kindly,assist me... thank you

0 Answers  

---

APPLICATIONS OF SHUNT GENERATOR

1 Answers   Wipro,

---

my question is that....few days ago i had installed a three phase motor starter for an electric saw.the motor will run and make the hydraulic pressure which will be goes to pressure cylender by up and down lever.two number of limitswitches are also installed on cylinder for safety of motor.now when the arm of cylinder reaches to the upper or lower limit it will cut the motor's line.and motor will be stop.now wana know that what will i do that motor runs continue after the limitswitch cut it down but it shold not be made any pressure.pls answer me in brief.

3 Answers  

---

who iz power minister ?? :P

1 Answers   IOCL,

---

draw the full wave and half wave circuit of 3 phase system and inverter circuit used in ups 

0 Answers  

---

what is the difference between indoor package substation and outdoor

3 Answers  

---

what are the different kind of cables used for transmissions?

0 Answers  

---

. Why the transmission lines are in 11kV, 22kV, 33kv, and why not 10kV, 20kV, 30kV?

3 Answers  

---

what is the maximum load in MDB,SMDB and DB

1 Answers  

---

What is the current carrying capacity of 0SWG,3SWG,10 & 12 SWG solid bare overhead copper conductors?

0 Answers   HAL,

---