What are the difference between current and voltage transformer


Current transformer monitor and measure the current through a transmission line and it will also isolate the metering equipment, and the voltage transformer does the monitoring and measuring of voltage in a transmission line. Electrical instruments are not connected to the meters or apparatus of high voltage directly for the safety of the instruments so the transformers like voltage and current transformers are used to connect the electrical instruments to the measuring instruments

Both the current and the voltage transformer has a magnetic circuit in it’s primary and the secondary windings but in case of its working, it is different. One of the functions of current and voltage transformers are the current transformer converts high value current to a low-value current were as the voltage transformer converts the high value of voltages into a lower value, a current transformer is designed to produce a current in its secondary coil which is proportional to the primary coil the voltage transformer converts the high voltage to low voltage and the low secondary voltage allows the protecting relay equipment and measuring equipment to be operated at lower voltages


It is used to step down the voltage of high value to the low value and low value is easy to measure, and the secondary voltage is substantially proportional to the primary voltage and differs in phase

Voltage transformers are designed to monitor three phase and single phase power line voltages in power metering applications it is a special type of transformer which allows the meters to take the reading from electrical connections with the higher voltage than the meter is capable to handle


  • It is used in transmission lines for the measurement of voltage, power metering and protection of lines
  • It can be used in electrical instrumentation system due to its ability to step down voltage and current and they provide electrical isolation too
  • These transformers are used to scale down the line to neutral voltage of wye system or the line to line voltage of the delta system


It is used to step down the current of the circuit to a lower value and the equipment are the same as the potential transformer and it is done by constructing the secondary coils with many turns of wire. And the primary coil has only a few turns of wire and by this, we can measure high values of current. If it is not connected to a load then it must be short-circuited because the magnetic circuit in the current transformer is designed for low magnetizing current when under the load and the increase in magnetizing current will build up large flux in the magnetic circuit and thus the transformer will act as a step-up transformer.


  • It is used for control circuits and in instrumentation for high current power application
  • It performs the role for current safety protection and current limiting
  • It can be used for the current monitoring of the power system
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