Current Transfomer

Could it be that the panel-mount meter is always 0-5A?

Hi Signode,

The various international standards are based on the use of either 1 A or 5 A meters, hence the 1 A or 5 A secondary current at rated full load primary current.

Hence (input amps / output amps) is the rated full load current of the circuit to be measured followed by the rated meter current at the specified burden.

However any ratio is possible. We have just made 15A/10mA CT's to special order.

I hope this helps.

BigBirdAustralia

HI ALL,

IT ALL DEPENDS ON THE ACCURACY.

FOR LT SIDE NORMALLY WE USE 5A CT's.

BUT IN HT SIDE WE USE 1A CT's.because in HT side we need to much concentrate on protection.we will be giving currents in the range of 100 mA to 1A TO THE RELAYS USED IN HT SIDE.but in LT side 1-5A. AND MORE OVER WE CONCENTRATE ON THE PROTECTION CLASS OT THE CT's.

thank you

naveen.m

They are commonly used in metering and protective relaying in the electrical power industry where they facilitate the safe measurement of large currents, often in the presence of high voltage.

The CT acts as a constant-current series device with a fraction of the high voltage primary circuit. Hence the primary circuit is largely unaffected by the insertion of the CT.

Common secondaries are 1 or 5 amperes. For example, a 4000:5 CT would provide an output current of 5 amperes when the primary was passing 4000 amperes. The secondary winding can be single ratio or multi ratio, with five taps being common for multi ratio CTs. Therefore almost CTs are quoted X/1A,..., Y/5A, not always arequoted Y/5A.