Answer / ramesh kumar k

Mr. RK is partially right.... I will tell you clearly...
CTs are of 3 types depending on their usage... they are
1. Metering 2.Protection & 3. Special Protection(PS)

Metering & Protection CTs name itself self explanatory.

In metering CTs our main aim is to measure the currents
without damaging the instruments (i.e. Ammeters) connected
to it... so at fault levels (i.e. high currents) the
secondary also indicates corresponding heavy currents... so
the meter connected to it will gets damaged... (A 5A
ameeter can't measure 50A)... inorder to make the meter
safe... we will prepare the core of the meter in such a way
that at faults currents the metering CT core gets
saturated... and it will not induce any more current in the
CT secondary... so the current in secondary ckt. is ZERO.
So the meter is safe... THIS METERING CT WILL BE WORKING
WITHIN NORMAL RANGE OF CURRENT AND WILLNOT WORK IN FAULT
CONDITIONS (IT WILL NOT GIVE OUTPUT).

Where as Protection CT will have to work only in fault
condition. Because the line has to be protected in fault
condition only. The core of this CT is made in reverse to
that of metering CT. It will not saturate in fault
condition and still give the output to the relay...

Thats why Metering CT can't be used for protection
purpose... and protection CT can be used for metering but
it will not meet the accuracy requirements (If accuracy
requiremets are compulsory... prot CT can't be used for
metering)


Where as

Answer / rk

metering cts are desined not to record fault current i.e.
if ctr is Ex. 200/5 at a fault current of 2000amp the
secondary current would be still 5 amps not 50amp. reverse
is in prot cts it will serve 50amps if its ALF permits .
Metring CT are like acc class 0.5 etc Protn CTs have 5P10,
5P20etc i.e. it will maintain its ratio up to 20times the
the primary current (200amp)of ct.

Answer / siddharth tayade

mainly the class is diffrence in the protection and
metering c.t.and knee point voltage is conciderd in
protection core

Answer / asit sarkar

Generally CT have two error 1.Phase angle error,2.Ratio error.
Now,in Metering CT we have to minimize the ratio error as
well as in case of Protection CT we have to reduce the phase
angle error.

what happens when reactive power increases ? does the reactive power loss increase or decrease ?

2 Answers  

---

i have 1500 kva generator how much maximum load avilable of use

1 Answers   Dr Reddys,

---

1 tr is equal to how many Kw .is there any specific formula for this to get the result .

13 Answers   Cipla, LG, NSN,

---

How many Cylinders are there in Diesel Generator?

4 Answers  

---

1KVA transformer of different frequencies of 50hz,100hz,500hz&1000hz. which one of these transformer has big size? Give reason

16 Answers   Ecil, Engineers India, MahaDiscom,

---

What is tranformer differtial?

0 Answers  

---

transformer phasor diagram under load explain it?

0 Answers  

---

why the transformer secondary voltage is more than the load end voltage like t/f 11KV/433V for 415V(terminal voltage)

4 Answers  

---

hi every body i am master student in control engineering and my project is slip control in trains i assumed a Dc motore as traction motor but i don't have characteristics of this kind of motor that is used in train. i want from every body if he or she has the characteristics or information about Dc motor that is used in train give me those information or technical characteristics .

0 Answers  

---

Why HRG and LRG used beside transformer, what is the purpose

3 Answers  

---

when we change tha taps from 1-16 in 100mva tr whether a constant voltage avaliable till it reaches tap 16 or voltage change as per taps change

1 Answers  

---

What is the difference between generator and turbo generator - related to power gereration

1 Answers  

---