A current transformer (VT) is a device that transforms high voltage to low voltage and is widely used in power systems. In an electricity meter, the VT converts a high-voltage electrical signal into a low-voltage signal that the meter can read to determine the amount of electricity.
When installing an electricity meter and VT, correctly distinguishing the polarity is crucial; otherwise, the meter reading will be incorrect. Here's how to determine the polarity of a current transformer:
Locate the polarity markings on the VT, usually "N1" or "N2".
Connect the VT to the circuit according to the markings.
Apply a test voltage to the circuit, typically 220V.
Observe the meter reading and record it.
Reverse the test voltage connection, that is, reverse the connection of the 220V input line to the VT.
Observe the meter reading again. If the reading is opposite to the previous one, the VT is connected incorrectly.
If the reading remains unchanged, the VT is connected correctly, and the meter reading should be accurate.
