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 factors influence the choice of an electrc drive?

0 Answers  

---

For a 500 MVA 400/220/33KV transformer following data given HV power = 500 MVA IV power = 500 MVA LV power = 5 MVA If input power is 500 MVA then how output power is (500+5)MVA. Can anyone help

1 Answers   MEIL,

---

The knee point of a current transformer is normally unique and known.So why in the nameplate of a CT they put the minimum value like this Vk> 400v.

0 Answers  

---

what is timing for mccb 800A tripping?

1 Answers   L&T,

---

can we synchronize star system generators with delta system generators?

0 Answers  

---

---

We have 250 KVAR cacitor bank & our average load is 200kva but our power factor is average 0.66 how can we maintane it? how can we balance our load?

4 Answers  

---

What is thermal relay and how it is works in transformer please explain

2 Answers   Future Group,

---

In our domestic single phase line if you don't have a ground connection (earthing)how will you separately use earth in a specific power supply board.

1 Answers  

---

how to decide the load on secondary of the tranformer

1 Answers   DLF,

---

In Star type and Delta type Motors, If one phase will miss/Break then which phase winding will burn and why?

4 Answers  

---

What is the role of a Production Engg in a Industry?????

1 Answers  

---

what is intermediate switch

1 Answers  

---