[The Diary of an Electrical Engineer] CURRENT TRANSFORMERS

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Mar 13, 2012, 4:59:21 AM3/13/12

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Current transformers are used to step down high current to very low current that can be handled comfortably.

High currents can not be measured directly using ammeters due to limitations of current carrying capacity of the measuring instruments.

Also, high currents can not be used in protective relays. To allow high current to pass, larger size of conductor is required .

This leads to practical difficulties in handling the devices

The practical solution to this difficulty is to step down the current to a very low value that can be as low as 1 amp or 5 amp.

Unlike a regular transformer, a current transformer steps down only current.

Voltage developed in the secondary will be negligibly less

(ie, current in the secondary x resistance of the winding)

The basic principle of CT functioning is ampere-turn matching

AT primary = AT secondary

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Posted By Vincent-KSEB to The Diary of an Electrical Engineer at 3/13/2012 01:59:00 AM

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