Articles

CURRENT TRANSFORMER

 

The main function of current transformer (CT) is to measure the current of another circuit. Current transformer collectively with Potential Transformer and Voltage Transformer are known as Instrument Transformers. When current in a circuit is exceptionally high which is directly applied to measuring instruments, a current transformer creates a reduced current precisely in required measure to the current in the circuit which is suitably connected to recording and measuring instruments. They are generally used in metering and protective relays in the electrical power engineering.
Wound and toroidal are the two principal types of current transformers. The integral primary winding in series is inserted in wound current transformer with the conductor that transmits the measured current. Toroidal current transformers do not consist a primary winding. The wire that carries the current is laced through a panel in the toroidal transformer.
Current transformers have many performance characteristics such as insulation voltage, primary current, secondary current, accuracy and burden.
Insulation voltage signifies the highest insulation that current transformers provide while connected to a power source. The load of the current transformer, known as primary current, is the measured current. The range of current output is secondary current. Accuracy confirms the level of certainty with which the measured current agrees with the standard value. Burden as expressed in volt-amperes (VA), a product of the voltage applied to a circuit and the current, is the maximum load that devices can sustain while operating within their accuracy ratings.
Current transformers offer variety of indoor, outdoor and industrial applications. The current can be measured in electronics equipment or motors by some of such devices. Apart from its uses in road lighting, the current transformers are used to assertain interrupted current feedback warning signs, identify ground defects and sense current overloads. Larger Current transformers are used in various three-phase systems to measure the voltage or current.