Answer / wareagle

You can also use capacitors to create a "phantom" 3rd phase
from the other 2. This may be what you have seen, but what
you probably didn't know is that this severely robs the
motor of power capacity. The motor runs severely unbalanced
and has a lot of what are called "negative sequence
currents" because of the 1 phase power and because the sine
waves are 180 degrees apart on the 2 "real" phases,
compared to being 120 degrees out on true 3 phase. Negative
sequence current produces negative torque in the motor and
causes heating without doing useful work, meaning that it
will severely overheat under load. For this reason, you
must derate the motor by at least 50%, some even say 66%.
So that means if you have a 15HP motor, you had better not
need more than 7-1/2 or even 5HP out of it if you are going
to do this.

Answer / electrical alie

It is know form physics that you can provide water about 45
ft away. This is clear from the objective test that is run.
However when you try to sole this problem from the books
you have read, you find conflict. This is because if i
tried solve objective from the other book then i could not
solve this from the 3rd book. Therefore you must use the
motor curves that power the overload system to determine if
you unknown will operate properly. It will help if you can
determine what is standard height of an energy meter is
from ground.

why permanent magnet generator have higher frequency of 400hz

3 Answers   Jaypee,

---

How can calculate the efficency of the rectifier. input 240V AC, current 5 amps,P.F 0.98, Output is 54 V DC,62.6 A.

10 Answers  

---

How to calculate the breaking capacity(like 15ka,20ka) of Circuit breaker (MCB,MCCB,ACB)

9 Answers   Career Excellent Sdn Bhd, Neona, Northern Max Engineering, Sps Renewables, Terasaki, UEM,

---

what are the specifications we must look at to select a relay for any capacity motor?

0 Answers  

---

What is the difference between single core 2 wire and single core 3 wire system? Which application we are using this? and for What purpose we are using this?

0 Answers  

---

---

What is RTCC in a transfomer and specify its function.

11 Answers   MCB, Vodafone,

---

how to calculate unit consumption on 3phase 380-415 v0lt kilowatt motor eg ( 55kw,380v,3phase 50-60hz)

1 Answers  

---

What voltage is used in Directional earth fault relay? and why?

5 Answers   L&T,

---

open circuit test when performed on double the voltage & double the freq, then what will happen with p.f and current magnitude?

1 Answers   Aarti Drugs,

---

Where can I get CPWD electrical shedule rates in web? please help me.

1 Answers  

---

why SCR use in power plant

1 Answers   Edison,

---

two phases with neutral supply can be taken in 3C X 10 sq.mm cable .

0 Answers   SPCL,

---