The structure and function of Power Current Transformer

Power Current Transformer plays an important function and role in the power supply system. Its basic structure is composed of iron core, primary winding, secondary winding, terminal and insulating support. The primary winding of the Power Current Transformer has a small number of turns and is connected in series in the line to be tested. For the through-core Power Current Transformer, the line to be tested passes through the transformer, P1 enters, and P2 exits. The greater the current to be tested, the The fewer turns. Combining the function and structure of the Power Current Transformer to analyze, the primary winding is connected in series in the circuit, and the number of turns is very small (one or several turns). Therefore, the current of the primary winding depends entirely on the current of the circuit under test. It has nothing to do with the magnitude of the secondary current. Under normal circumstances, the coil impedance of the AC ammeter or current relay connected to the secondary winding of the Power Current Transformer is very small, so the normal working state of the secondary circuit of the Power Current Transformer is close to the short-circuit state.

Based on the structural characteristics of the Power Current Transformer, it is worth noting that the secondary side of the Power Current Transformer in a normal working state must never be open, because once the secondary side is open, the impedance of the secondary loop becomes infinite, and the secondary current is equal to zero , Then the primary current completely becomes the excitation current, and extremely high voltage is generated in the secondary winding, which directly endangers the safety of people and equipment on the secondary side. Therefore, it is not allowed to install a fuse on the secondary side of the Power Current Transformer, lest the fuse is blown, and the secondary side becomes an open circuit.

When Power Current Transformer uses the Power Current Transformer, it must first pay attention to ensure that its range meets the requirements for use. Once the current to be measured exceeds the range of the ammeter, it needs to replace a higher range AC ammeter and a matching Power Current Transformer.

In addition, in practical applications, it is also necessary to ensure that the iron core and the secondary side of the Power Current Transformer must be reliably grounded to prevent accidental charging of the iron core. Once the primary insulation is broken down, the secondary side will enter high voltage. It directly threatens the personal safety of the secondary side and causes equipment damage.