about current transformer

how ct become a current out put device

Ip x Np = Is x Ns

Ip= primary current
Np = primary number of turns
Is= secondary current
Ns = secondary number of turns

hai dude this formula is applicable for pt also .
then i can use a pt as ct?

wisepie said:

Ip x Np = Is x Ns

Ip= primary current
Np = primary number of turns
Is= secondary current
Ns = secondary number of turns

Click to expand...

Actually current transformer is a current sensing device. Along with current sensing it provides isolation also.

Let 100A of current is flowing in the circuit. Current transformer senses this curren and transforms this current into a lower value as per turns ratio, and the proportion voltage drop due to secondary current is measured across the burden resistancee in the transformer.

Normal transformer are parallel in nature, whereas current transformer as series circuit

i agree wt ur telling
then how it is transferring primary current to secondery
i know it is using mutual induction . even in pt also it is same . but here o/p is current and in pt it is vtg . what is difference in these two
wt determine o/p shuld be current or vtg

saurav_sdpl said:

Actually current transformer is a current sensing device. Along with current sensing it provides isolation also.

Let 100A of current is flowing in the circuit. Current transformer senses this curren and transforms this current into a lower value as per turns ratio, and the proportion voltage drop due to secondary current is measured across the burden resistancee in the transformer.

Normal transformer are parallel in nature, whereas current transformer as series circuit

Click to expand...

yes ,i think so.

I told u CT is a series connection, whereas VT is Parallel, that is in VT u give 230V at one end and 0V at other, wheres as in CT u put CT in Wire where current has to be measured, so both the ends are Connected to same phase with very less impedence of inductor

The O/p of current transformer is current proportional to turns ratio, It is also based on the principle of flux linkgae, due to mutual inductance between primary & secondary, Just like in voltage transformer, some amount of primary current is used to magnetize the core, so not excatly all the primary power is converted in the proportional value in secondary, same happens in current transformer.

In secondary u always get current, which when flows accros the burden resistor gives the proportional voltage., which is inturn read out,

Hope u got the point

saubhik said:

hai dude this formula is applicable for pt also .
then i can use a pt as ct?

wisepie said:

Ip x Np = Is x Ns

Ip= primary current
Np = primary number of turns
Is= secondary current
Ns = secondary number of turns

Click to expand...

Click to expand...

Hi dude, actually current transformer and impedance matching trans are clasified as pt also...anyway... this formula is applied to all kind of transformers.

as saurav_sdpl said, CT is a series connection. The theory is same. Voltage drop across will induces volatge in secondary. But since the voltage drop at primary is very small, you can even set the primary number of turn as less as only a turn.