current transformer (CT) is a type of transformer that is used to reduce or multiply an alternating current (AC). It produces a current in its secondary which is proportional to the current in its primary.

Current transformers, along with voltage or potential transformers, are instrument transformers.



Current transformers are utilized broadly for estimating current and observing the activity of the power framework. Alongside voltage leads, income grade CTs drive the electrical utility’s watt-hour meter on numerous bigger business and modern supplies.

High-voltage current transformers are mounted on porcelain or polymer covers to separate them from ground. Some CT setups slip around the bushing of a high-voltage transformer or electrical switch, which consequently focuses the conduit inside the CT window.

Current transformers can be mounted on the low voltage or high voltage leads of a power transformer. Now and then a segment of a bus bar can be taken out to supplant a current transformer.

The National Electrical Code (NEC) requires leftover current gadgets in business and private electrical frameworks to safeguard outlets introduced in “wet” area like kitchens and washrooms, as well as weatherproof outlets introduced outside. Such gadgets, most normally ground issue circuit interrupters (GFCIs), ordinarily run both the 120-volt invigorated guide and the nonpartisan return guide through a current transformer, with the optional curl associated with an outing gadget.

Under typical circumstances the current in the two circuit wires will be equivalent and stream in inverse headings, bringing about zero net current through the CT and no current in the auxiliary loop. On the off chance that the stock current is diverted downstream into the third (ground) circuit guide (for example in the event that the grounded metallic instance of a power device contacts a 120-volt channel), or into earth ground (for example on the off chance that an individual contacts a 120-volt guide), the nonpartisan return current will be not exactly the stock current, bringing about a positive net current course through the CT. This net current stream will prompt current in the optional curl, which will make the excursion gadget work and de-empower the circuit – normally inside 0.2 seconds.[citation needed]

The weight (load) impedance shouldn’t surpass the predefined greatest worth to keep away from the optional voltage surpassing the cutoff points for the current transformer. The essential current rating of a current transformer ought not be surpassed or the center might enter its non straight district and at last immerse. This would happen close to the furthest limit of the main portion of every half (positive and negative) of the AC sine wave in the essential and would think twice about precision

33 kV CT, is a kind of “instrument transformer” that is intended to deliver a substituting current in its optional winding which is corresponding to the current being estimated in its essential. Current transformers lessen high voltage currents to a much lower esteem and give a helpful approach to securely observing the genuine electrical current streaming in an AC transmission line utilizing a standard ammeter. The head of activity of a fundamental current transformer is marginally unique in relation to that of a normal voltage transformer.

Regular Current Transformer

Dissimilar to the voltage or power transformer took a gander at beforehand, the current transformer comprises of only one or not many turns as its essential winding. This essential winding can be of either a solitary level turn, a loop of rock solid wire folded over the center or simply a conduit or transport bar put through a focal opening as displayed.

Because of this kind of game plan, the current transformer is frequently alluded excessively as a “series transformer” as the essential winding, which never has in excess of a not very many turns, is in series with the current conveying guide providing a heap

There are three basic types of current transformers: woundtoroidal and bar.

Technical Specifications:- 

1. Name and address of Manufacturer :  Twiclo Electrical Industries, Raipur
2. Type :  Outdoor, Oil filled, Vacuum Impregnated
3. Manufacturer’s Designation :  COF
4. Rated Voltage/Highest Voltage :  33 kV / 36 kV *
5. Rated Primary Current :  As per spec Amps *
6.  Secondary Core details :
     a. Number of Cores :  One
     b. Rated Secondary Current :  1 or 5 Amp *
     c. Rated Output :  as per spec VA *
     d. Class of accuracy :  as per spec VA *
     e. Accuracy limit factor :  as per spec VA *
7.  Turns Ratio :   Nominally same as transformation ratio
8.  Short time thermal current & its duration :  As per spec kA
9.  Rated dynamic current (peak value) :  2.5 times of short time thermal current kA*
10.     a. Rated continuous thermal current :  Same as rated primary current *
           b. Temperature rise over ambient :  Within limits prescribed by IS. *
11.  Impulse withstand test voltage :  170 kV (Peak)*
12.  One-minute power frequency dry/wet withstand test voltage on primary :  70 kV *
13.  One-minute power frequency withstand test voltage on secondary :  3 kV *
14.  Total creepage of insulator :  900 mm minimum *
15.  Whether CT is hermetically sealed :  Yes.
16.  Quantity of oil :  Approx. 16 Liters.
17.  Total weight :  Approx. 70 Kgs
18.  Mounting Details :  As per drawing
19.  Equipment conforms to specification :  IS 2705
20.  Overall dimensions :  As per our drawing

Note: Only items marked * are guaranteed. All others are indicative and subject to change.


Also Check our other product ranges Voltage Transformer , Current Transformer  & potential-transformers