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What are Current Transformers?

10/18/2013 10:36:12 AM | by Anonymous

Current Transformers

A current transformer is used for measuring of the alternate electric currents. These current transformers are together with the voltage transformers or are also known as instrument transformers.


When the current in a circuit is too high or directly apply to measure the instruments, the current transformer can produce a reduced current accurately proportional to the current in the circuit which can be conveniently connected to record or measure the instruments. They can also isolate the measuring instruments from what may be very high voltage in the monitored circuit. They are commonly used in protective relays and metering in the electrical power industry.


They are a kind of electrical instrument that produces and provides a flow of current in the secondary circuit that is correctly perpendicular to the amount of current flowing in its primary circuit. In order to calculate the current and monitor the operation of the power grid, they are widely used and are classically defined by the current ration from primary to secondary.


Current transformers are often widely used and seen in metering and protective relaying in the electrical power industry where they make easy for the safest obligation of a huge amount of currents and are regularly in the presence of high voltages on the circuit. They are securely cut offs to manage and measure a circuitry from a high voltage that is essentially available on the circuit.


Normally, they are controlled by passing a single primary under a well-insulated toronial core with enormous turns of wire wrapped. They can also be used to measure the flow of the current as well as monitoring the operation of the power used. However, there are some factors that improve the current transformer’s accuracy such as physical current transformer configuration and rating factor.


The reasons for burden in current calculation circuit is that they are intermediate conductors and switch blocks meters as well as the sources are from the conductors among the current transformer and meter. The problem of producing high resistance occurs due to placing a substation meter at some level of distance from meter by using current transformer with 1 amp that produces low voltage drop.


As for the rating factor of the current transformers, they are dependent on ambient temperature and are factor used to determine the correct maximum measurable primary current by multiplying the full load of a current transformer. To maintain the accuracy level in rising of ambient temperature, they must have low capacity and the rating factors of the current transformers that range from 35 to 55 degrees Celsius.


Another important factor for accuracy of current transformer is the physical current transformer configuration. In case the conductors are not really centered in the oval or circular, the inaccuracy will occur in current transformer and may need to be notified for the correct accuracy.

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