Difference between current transformer and Voltage transformer

One of the main differences between CT and PT transformers is their functionality.

On the one hand, current transformers can reduce high currents to a safer and easier to manage level for you to measure. It converts large primary currents into small 1A/5A currents, which can be measured on an ammeter.

On the other hand, the potential (Voltage transformer) measures and reduces the high voltage value to a smaller value. It converts the high voltage into a standard secondary voltage of 100V or lower.

Type

Current transformers are divided into two types, including wound and closed core. Voltage transformer is also divided into two types, including electromagnetic voltage and capacitive voltage.

Contact

In a current transformer, the primary winding is connected in series to the transmission line for measuring its current, and the entire line current flows through the winding. On the other hand, the Voltage transformer is connected in parallel with the circuit, which means that the full line voltage appears at both ends of the winding.

Conversion rate

The transformation ratio of current transformer is very high, while that of Voltage transformer is very low.

Primary and secondary windings

In current transformers, the primary winding has fewer turns and carries the current to be measured. In a Voltage transformer, the primary winding has many turns and carries the voltage to be measured.

In a current transformer, the secondary winding has a large number of turns on the secondary side and is connected to the current winding of the instrument. In Voltage transformer, the secondary winding has a small number of turns on the secondary side and is connected to the instrument or meter.

Structure

The current transformer is designed with silicon steel laminations, while the Voltage transformer is designed with high-quality steel that operates under low magnetic flux density.

Primary current

In current transformers, the primary current does not depend on the secondary circuit conditions. On the other hand, in Voltage transformer, the primary current depends on the circuit conditions at the secondary side.

Apply

Using a current transformer, you can use a 5-ampere ammeter to measure large currents such as 200 amperes. On the other hand, with a Voltage transformer, you can use a 120V Voltmeter to measure 11KV and other high voltages.

Secondary side

In current transformers, the secondary side cannot be opened during operation. On the other hand, in Voltage transformer, you can open the secondary side without any damage.

Input value

In a current transformer, the input value is a constant current, while in a potential current, the input is a constant voltage.

Secondary winding range

The range is 1A or 5A in current transformers and 110V in Voltage transformer.

Burden

Current transformers do not rely on secondary loads, while Voltage transformer rely on secondary loads.

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