NEED FOR CURRENT TRANSFORMERS IN POWER CIRCUITS


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           NEED FOR CURRENT TRANSFORMERS IN POWER CIRCUITS

Current transformers have great importance in the transmission and the distribution of the electrical energy by using the current transformers it will give effective protection to the transmission and the distribution circuits and to the connected plant. Current transformers are used to reduce the current levels from 1000 of amperes down to the standard output of 5A or 1A for the normal operation. Current transformer produces an output which is proportional to the current flowing through the primary winding as a result of a constant potential on the primary

CURRENT TRANSFORMER FUNCTION
• power system current will be reduced to a lower value for the measurement
• secondary circuits will be insulated from the primary
• Use of the standard current ratings for the secondary

PROTECTION BAR PRIMARY CURRENT TRANSFORMER

The current transformer is used to produce alternating current in its secondary which will proportional to the Ac current in its primary. It is used when the current or voltage is too high to measure directly and the induced secondary current will be used for measuring instruments or electronic equipment processing and it would need isolation between primary and secondary
The current transformer is different from the voltage or the power transformer the current transformer only has one or few turns in its primary winding the primary winding could be a single flat turn or a conductor and due to this type of arrangement the current transformers also known as a series transformer

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Secondary winding have a larger number of turns the current transformer’s primary current is not dependent on the secondary load current instead it is controlled by an external load current

EQUIVALENT CIRCUIT FOR CURRENT TRANSFORMER

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TYPES OF CURRENT TRANSFORMERS

• Wound current transformer – primary winding of the transformer is connected with the conductor in series which carries the current flowing in the circuit. the magnitude of the secondary current depends on the ratio of turn in the transformer
• Toroidal current transformer – it doesn’t have a primary winding instead of that the line carries the current flowing in the network is threaded through a hole
• Bar type current transformer – this transformer uses actual cable or bus bar of the main circuit as the primary winding which is mainly a single turn