Siemens APT Current Transformer - The difference between voltage transformer and current transformer

Create Date: 2024-8-30 12:03:23|Source: APT/Siemens Shanghai Ergong

The difference between the voltage transformer and the current transformer in terms of effect principle The primary difference is that the operating conditions are very different during normal operation, and the main performance is as follows:

1) The current transformer can be short-circuited twice, but it cannot be opened; The voltage transformer can be opened twice, but it must not be short-circuited

2) As far as the load on the secondary side is concerned, the primary internal impedance of the voltage transformer is small or even negligible, and the voltage transformer can be considered as a voltage source; However, the internal resistance of the current transformer is so large that it can be regarded as a current source with infinite internal resistance.

3) The magnetic flux density of the voltage transformer is close to the full value during normal operation, and the magnetic flux density decreases when it is faulty; The magnetic flux density is very low during the normal operation of the current transformer, and the magnetic flux density increases greatly due to the short-circuit current on the primary side during the short circuit, and sometimes it even far exceeds the full value.

4) The voltage transformer is a special transformer used to measure the high voltage of the power grid, which can convert the high voltage into a lower voltage according to the specified share, and then connect it to the instrument to measure. For voltage transformers, no matter how many volts the primary side voltage is, and the secondary side voltage is generally specified at 100 volts to supply the voltage required by the voltage coils of voltmeters, power meters, kilowatt hour meters and relays.

Electrical equipment that converts a large current into a small current according to a specified share is called a current transformer. The current on the secondary side of the current transformer is generally specified as 5 amps or 1 ampere to supply the current coil current of the ammeter, power meter, kilowatt hour meter and relay.
Siemens APT Current Transformer - The difference between voltage transformer and current transformer


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