In many kinds of current transformer, there is a special one, which is zero sequence current transformer. Although the scope is the same, it is different from general current transformer. Today, the task of small series is to find out these differences of zero sequence current transformer 11.
The current transformer is used to detect the current of a certain phase or electrical protection line, while the zero sequence current transformer is mainly used to detect the neutral unbalanced current. It can detect whether the vector sum of single-phase two-wire current or three-phase four wire current is zero. When it is not zero, it will output the trigger signal, but it is usually used together with the relay protector. How does it do it?
The primary three-phase wire of the zero sequence current transformer passes through the iron core, and the secondary coil is wound on the iron core. Because the primary three-phase current of the zero sequence current transformer is symmetrical and the vector sum is zero, there is no magnetic flux in the iron core, and there is no current in the secondary coil. In case of failure, the sum of three-phase current will not be zero, and zero sequence flux will appear in the core. In this way, the magnetic flux senses the potential on the secondary coil, and the secondary current flows through the relay, which is used to measure and protect the current.https://www.ctsensorducer.com/