Electrical instrument transfomer is type of transfomers which is use for unique meetering , protection and testing uses. Power system is the system which connect power generation plant to utilizations point. The protection of the power system is essential because the supply of electricity should uninterrupted during the operation. Following are the protection devices which use in electrical power system. Normally current transfomers are voltage transfomers in electrical engineeirng known as instrument transfomer.
Two Electrical Instrument Transfomer
Current Transformer (CT)
These kind of transformers are used to step down the large current. Current transformers also use to step down large current to get low the value. So that the protective relays of the electrical system can detect the informations from it. After protective relay detect the system it can take an action in any case of fault. Current transformers are normally connected on the Low Voltage lines.
The current in the power system are beyond the measurement capacity of the normal metering instruments such as ampere meter. So the Current transformers are employed to step down the quantity for the measurement purposes.
Current transformers are used to step down the current into known ratio to allow for the proper operation of the measurement device. Another application of current transfomers are, It also use to provide lowe current in to the seconday side.
The main purpose of current transfomer in electrical power system are metering. This is also use in protective relays in electrical power systems.
The accuracy of the current transfomers are really important. The accuracy of this instrument type transfomer is much depend on several factors such as phase change, load, atmosphereic temperature, and resistance of primary and secondary.
Potential Transformer (PT)
Potential transformers are used to step down the high voltage. Lower voltage is take at secondary side of potential transformers by controlling the number of turns of this.
Both current transformers and potential transformers give necessary informations to protective relays so the can control the switches and circuit breakers according to the situations. Potential transformers are normally connect on the Medium voltage lines.
The voltage in the power system are beyond the measurement capacity of the normal metering instruments such as voltmeter.
So the potential transformers are employed to step down the quantity for the measurement purposes. Voltage transformers are used to step down the current into known ratio to allow for the proper operation of the measurement device.