Precision current transformers comply with the principle of series and operation process

- Feb 18, 2019-

The wiring of the precision current transformer should follow the principle of series. When performing the operation, the primary winding should be connected in series with the circuit under test, and the secondary winding should be selected with all the instrument loads, according to the current being measured during operation. A suitable ratio will otherwise increase the error. At the same time, one end of the secondary side must be grounded to prevent the primary side from breaking into the secondary low-voltage side when the insulation is damaged, causing personal and equipment accidents.


The secondary side of the precision current transformer is absolutely not allowed to open, because once the circuit is open, the primary current I1 becomes the magnetizing current, causing the φm and E2 to increase suddenly, causing the core to be oversaturated and magnetized, causing severe heat or even burning the coil; at the same time, the magnetic circuit is oversaturated. After magnetization, the error is increased. When the current transformer is in normal operation, the secondary side is used in series with a current coil such as a measuring instrument and a relay. The current coil of the measuring instrument and the relay has a small impedance, and the secondary side approximates a short circuit.


During the operation of the precision current transformer, the secondary side opens the circuit to a voltage of several hundred volts on the secondary side. Once touched, it will cause an electric shock accident. Therefore, the secondary side of the current transformer is provided with a short-circuit switch to prevent the secondary side from opening. In the process of use, once the secondary side opens, the circuit load should be removed immediately, and then the power is cut off. It can be reused after everything is